GIFT   OF 
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Library 


JUST  PUBLISHED 

AVIATION  ENGINES.     Their  Design,  Construction, 
Operation  and  Repair. 

By  Lieut.  VICTOR  W.  PAGE,  Aviation  Section,  S.C.U.S.R. 

A  practical  work  containing  valuable  instructions  for  aviation 
students,  mechanicians,  squadron  engineering  officers  and  all  inter- 
ested in  the  "construction  and  upkeep  of  airplane  power  plants. 
576  octavo  pages.  250  illustrations.  Price  $3.00. 

AVIATION  CHART,  or  the  Location  of  Airplane  Power 
Plant  Troubles  Made  Easy. 

By  Lieut.  VICTOR  W.  PAGE,  A.S.,  &C.U.S.R. 

A  large  chart  outlining  all  parts  of  i  typical  airplane  power  plant, 
showing  the  points  where  trouble  is  apt  to  occur  and  suggesting 
remedies  for  the  common  defects.  Intended  especially  for  aviators 
and  aviation  mechanics  on  school  and  field  duty.  Price  50  cents. 

GLOSSARY  OF  AVIATION  TERMS. 

Compiled  by  Lieuts.  VICTOR  W.  PAGE,  A.S.,  S.C.U.S.R.  and 
PAUL  MONTARIOL  of  the  French  Flying  Corps  on  duty  at 
Signal  Corps  Aviation  School,  Mineola,  L.  I. 
A  complete  glossary  of  practically  all  terms  used  in  aviation, 
having  lists  in  both  French  and  English,  with  equivalents  in  either 
language.    A  very  valuable  book  for  all  who  are  about  to  leave 
for  duty  overseas.    Price,  cloth,  $1.00. 


THE  NORMAN  W.  HENLEY  PUBLISHING   COMPANY 
2  WEST  45TH  ST.,  NEW  YORK 


Rocker  Lever 


Cam  Shaft- ", 


Oil  Jacket 


Inlet  Pipe ""    '-»>. 


Fulcrum 


^•Regulating  Screw 
s'Key  ,„ -Valve  Spring  Collar 

'  ,- Valve  Spring 

— Valve  Stem 

Valve  Stem  Guide 
'"-•Exhaust  Pipe 


Contact  Breaker 

Safety  Gas-''' 
Wrist  Pin-"'' 
Connecting  Rod " 

****  *" 

CrankShaft-'' 

Crank  Pin '" 

Bearing  Box-'"' 

Sump-*''' 


;    /  ^Upper  Half  Case 
-Lower  Half  Case 


"' — Drain  Plug  orNuf 


Drain  Cock--"' 


A.6.HA6STROM  N.Y. 


Part  Sectional  View  of  Hall-Scott  Airplane  Motor,  Showing 
Principal  Parts. 


AVIATION  ENGINES 

Design — Construction — Operation  and  Repair 


A  COMPLETE,  PRACTICAL  TREATISE  OUTLINING  CLEARLY 
THE  ELEMENTS  OF  INTERNAL  COMBUSTION  ENGINEERING 
WITH  SPECIAL  REFERENCE  TO  THE  DESIGN,  CONSTRUC- 
TION, OPERATION  AND  REPAIR  OF  AIRPLANE  POWER 
PLANTS;  ALSO  THE  AUXILIARY  ENGINE  SYSTEMS,  SUCH 
AS  LUBRICATION,  CARBURETION,  IGNITION  AND  COOLING. 

IT    INCLUDES    COMPLETE    INSTRUCTIONS    FOR    ENGINE 

REPAIRING  AND   SYSTEMATIC  LOCATION   OF  TROUBLES, 

TOOL  EQUIPMENT  AND  USE  OF  TOOLS,  ALSO  OUTLINES 

THE  LATEST  MECHANICAL  PROCESSES. 


BY 

FIRST  LIEUT.  VICTOR  W.  PAGE,  A.  S.  S.  C.,  U.  S.  R. 

M 

Assistant  Engineering  Officer,  Signal  Corps  Aviation  School,  Mineola,  L.  I. 
Author  of  "The  Modern  Gasoline  Automobile,"  Etc. 


CONTAINS  VALUABLE  INSTRUCTIONS  FOR  ALL  AVIATION  STUDENTS,  MECH- 
ANICIANS,   SQUADRON    ENGINEERING    OFFICERS    AND   ALL  INTERESTED   IN 
THE  CONSTRUCTION  AND  UPKEEP  OF  AIRPLANE  POWER  PLANTS. 


NEW  YORK 

THE  NORMAN  W.  HENLEY  PUBLISHING  COMPANY 

2  WEST  45th  STREET 
1918 


P3 

Engineering 
Library 


COPYRIGHTED,  1917 

BY 

THE  NORMAN  W.  HENLEY  PUBLISHING  Co. 


PRINTED  IN  U.  S.  A. 


THIRD   IMPRESSION 


ALL  ILLUSTRATIONS  IN  THIS  BOOK  HAVE  BEEN 
SPECIALLY  MADE  BY  THE  PUBLISHERS,  AND  THEIR 
USE,  WITHOUT  PERMISSION,  IS  STRICTLY  PROHIBITED 


PRESS    OF 

BRAUNWORTH     &    CO. 

BOOK    MANUFACTURERS 

BROOKLYN.     N,    Yo 


PREFACE 

IN  presenting  this  treatise  on  "Aviation  Engines," 
the  writer  realizes  that  the  rapidly  developing  art  makes 
it  difficult  to  outline  all  latest  forms  or  describe  all 
current  engineering  practice.  This  exposition  has  been 
prepared  primarily  for  instruction  purposes  and  is  adapted 
for  men  in  the  Aviation  Section,  Signal  Corps,  and 
students  who  wish  to  become  aviators  or  aviation  mech- 
anicians. Every  effort  has  been  made  to  have  the  engi- 
neering information  accurate,  but  owing  to  the  diversity 
of  authorities  consulted  and  use  of  data  translated  from 
foreign  language  periodicals,  it  is  expected  that  some 
slight  errors  will  be  present.  The  writer  wishes  to  ac- 
knowledge his  indebtedness  to  such  firms  as  the  Curtiss 
Aeroplane  and  Motor  Co.,  Hall-Scott  Company,  Thomas- 
Morse  Aircraft  Corporation  and  General  Vehicle  Com- 
pany for  photographs  and  helpful  descriptive  matter. 
Special  attention  has  been  paid  to  instructions  on  tool 
equipment,  use  of  tools,  trouble  "shooting"  and -engine 
repairs,  as  it  is  on  these  points  that  the  average  aviation 
student  is  weakest.  Only  such  theoretical  consideration 
of  thermo-dynamics  as  was  deemed  absolutely  necessary 
to  secure  a  proper  understanding  of  engine  action  after 
consulting  several  instructors  is  included,  the  writer's 
efforts  having  been  confined  to  the  preparation  of  a 
practical  series  of  instructions  that  would  be  of  the 
greatest  value  to  those  who  need  a  diversified  knowledge 
of  internal-combustion  engine  operation  and  repair,  and 

9 

398185 


10  Preface 

who  must  acquire  it  quickly.  The  engines,  described  and 
illustrated  are  all  practical  forms  that  have  been  fitted  to 
airplanes  capable  of  making  flights  and  may  be  considered 
fairly  representative  of  the  present  state  of  the  art. 

VICTOR  W.  PAGE, 
1st  Lieut.  A.  S.  S.  C.,  U.  S.  R. 

MlNEOLA,  L.  I., 

March,  1918. 


CONTENTS 

CHAPTER  I 

PAGES 

Brief  Consideration  of  Aircraft  Types — Essential  Requirements  of  Aerial 
Motors — Aviation  Engines  Must  Be  Light — Factors  Influencing 
Power  Needed — Why  Explosive  Motors  Are  Best — Historical — Main 
Types  of  Internal  Combustion  Engines 17-36 

CHAPTER   II 

Operating  Principles  of  Two-  and  Four-Stroke  Engines — Four-cycle 
Action — Two-cycle  Action — Comparing  Two-  and  Four-cycle  Types 
— Theory  of  Gas  and  Gasoline  Engine — Early  Gas-Engine  Forms — 
Isothermal  Law — Adiabatic  Law — Temperature  Computations — 
Heat  and  Its  Work — Conversion  of  Heat  to  Power — Requisites  for 
Best  Power  Effect  37-59 


CHAPTER   III 

Efficiency  of  Internal  Combustion  Engines — Various  Measures  of  Effi- 
ciency— Temperatures  and  Pressures — Factors  Governing  Economy 
— Losses  in  Wall  Cooling — "Value  of  Indicator  Cards — Compression 
in  Explosive  Motors — Factors  Limiting  Compression — Causes  of 
Heat  Losses  and  Inefficiency — Heat  Losses  to  Cooling  Water  .  60-79 


CHAPTER  IV 

Engine  Parts  and  Functions — Why  Multiple  Cylinder  Engines  Are  Best 
— Describing  Sequence  of  Operations — Simple  Engines — Four  and 
Six  Cylinder  Vertical  Tandem  Engines — Eight  and  Twelve  Cylinder 
V  Engines — Radial  Cylinder  Arrangement — Rotary  Cylinder 
Forms  .  80-109 


CHAPTER  V 

Properties  of  Liquid  Fuels — Distillates  of  Crude  Petroleum — Principles 
of  Carburetion  Outlined — Air  Needed  to  Burn  Gasoline — What  a 
Carburetor  Should  Do — Liquid  Fuel  Storage  and  Supply — Vacuum 
Fuel  Feed  —  Early  Vaporizer  Forms  —  Development  of  Float 

11 


12  Contents 


PAGES 

Feed  Carburetor — Maybach's  Early  Design — Concentric  Float  and 
Jet  Type  —  Sehebler  Carburetor  —  Claudel  Carburetor  —  Stewart 
Metering  Pin  Type — Multiple  Nozzle  Vaporizers — Two-Stage  Car- 
buretor— Master  Multiple  Jet  Type — Compound  Nozzle  Zenith  Car- 
buretor— Utility  of  Gasoline  Strainers — Intake  Manifold  Design  and 
Construction — Compensating  for  Various  Atmospheric  Conditions — . 
How  High  Altitude  Affects  Power — The  Diesel  System — Notes  on 
Carburetor  Installation — Notes  on  Carburetor  Adjustment  .  110-154 


CHAPTER  VI 

Early  Ignition  Systems — Electrical  Ignition  Best — Fundamentals  of 
Magnetism  Outlined — Forms  of  Magneto — Zones  of  Magnetic  In- 
fluence— How  Magnets  are  Made — Electricity  and  Magnetism  Be- 
lated— Basic  Principles  of  Magneto  Action — Essential  Parts  of 
Magneto  and  Functions — Transformer  Coil  Systems — True  High 
Tension  Type — -The  Berling  Magneto — Timing  and  Care — The  Dixie 
Magneto — Spark-Plug  Design  and  Application — Two-Spark  Ignition 
Special  Airplane  Plug  .  155-200 


CHAPTER  VII 

Why  Lubrication  Is  Necessary — Friction  Defined — Theory  of  Lubrica- 
tion— Derivation  of  Lubricants — Properties  of  Cylinder  Oils — Fac- 
tors Influencing  Lubrication  System  Selection — Gnome  Type  Engines 
Use  Castor  Oil — Hall-Scott  Lubrication  System — Oil  Supply  by 
Constant  Level  Splash  System — Dry  Crank-Case  System  Best  for 
Airplane  Engines — Why  Cooling  Systems  Are  Necessary — Cooling 
Systems  Generally  Applied — Cooling  by  Positive  Pump  Circulation 
—  Thermo-Syphon  System  —  Direct  Air-Cooling  Methods  —  Air-  • 
Cooled  Engine  Design  Considerations 201-232 


CHAPTER  VIII 

Methods  of  Cylinder  Construction — Block  Castings — Influence  on  Crank- 
Shaft  Design — Combustion  Chamber  Design — Bore  and  Stroke  Eatio 
— Meaning  of  Piston  Speed — Advantage  of  Off-Set  Cylinders — 
Valve  Location  of  Vital  Import — Valve  Installation  Practice — Valve 
Design  and  Construction — Valve  Operation — Methods  of  Driving 
Cam-Shaft — Valve  Springs — Valve  Timing — Blowing  Back — Lead 
Given  Exhaust  Valve — Exhaust  Closing,  Inlet  Opening — Closing  the 
Inlet  Valve — Time  of  Ignition — How  an  Engine  is  Timed — Gnome 
"Monosoupape"  Valve  Timing — Springless  .Valves — Four  Valves 
per  Cylinder 233-286 


Contents  13 

CHAPTER  IX 

PACES 

Constructional  Details  of  Pistons — Aluminum  Cylinders  and  Pistons — 
Piston  Eing  Construction — Leak  Proof  Piston  Eings — Keeping  Oil 
Out  of  Combustion  Chamber — Connecting  Eod  Forms — Connecting 
Eods  for  Vee  Engines — Cam-Shaft  and  Crank-Shaft  Designs — Ball 
Bearing  Crank-Shafts — Engine  Base  Construction  ....  287-323 

CHAPTER  X 

Power  Plant  Installation — Curtiss  OX-2  Engine  Mounting  and  Operating 
Eules  —  Standard  S.  A.  E.  Engine  Bed  Dimensions  —  Hall-Scott 
Engine  Installation  and  Operation-1— Fuel  System  Eules — Ignition 
System — Water  System — Preparations  to  Start  Engine — Mounting 
Eadial  and  Eotary  Engines  —  Practical  Hints  to  Locate  Engine 
Troubles — All  Engine  Troubles  Summarized — Location  of  Engine 
Troubles  Made  Easy 324-375 

CHAPTER  XI 

Tools  for  Adjusting  and  Erecting — Forms  of  Wrenches — Use  and  Care 
of  Files — Split  Pin  Eemoval  and  Installation — Complete  Chisel  Set 
— Drilling  Machines — Drills,  Eeamers,  Taps  and  Dies — Measuring 
Tools — Micrometer  Calipers  and  Their  Use — Typical  Tool  Outfits — 
Special  Hall-Scott  Tools — Overhauling  Airplane  Engines — Taking 
Engine  Down — Defects  in  Cylinders — Carbon  •  Deposits,  Cause  and 
Prevention — Use  of  Carbon  Scrapers — Burning  Out  Carbon  with 
Oxygen — Eepairing  Scored  Cylinders^— Valve  Eemoval  and  Inspec- 
tion— Eeseating  and  Truing  Valves — Valve  Grinding  Processes — 
Depreciation  in  Valve  Operating  System — Piston  Troubles — Piston 
Eing  Manipulation — Fitting  Piston  Eings — Wrist-Pin  Wear — In- 
spection and  Eefitting  of  Engine  Bearings — Scraping  Brasses  to  Fit 
• — Fitting  Connecting  Eods — Testing  for  Bearing  Parallelism — Cam- 
Shafts  and  Timing  Gears — Precautions  in  Eeassembling  Parts  .  376-456 

CHAPTER  XII 

Aviation  Engine  Types — Division  in  Classes — Anzani  Engines — Canton 
and  Unne  Engine — Construction  of  Gnome  Engines — "Monosou- 
pape ' '  Gnome — German  f '  Gnome ' '  Type — Le'  Ehone  Engine — 
Eenault  Air-Cooled  Engine — Simplex  Model  "A"  Hispano-Suiza — 
Curtiss  Aviation  Motors — Thomas-Morse  Model  88  Engine — Duesen- 
berg  Engine  —  Aeromarine  Six-Cylinder  —  Wisconsin  Aviation 
Engines  —  Hall-Scott  Engines  —  Mercedes  Motor  —  Benz  Motor  — 
Austro-Daimler  Engine — Sunbeam-Coatalen — Indicating  and  Meas- 
uring Instruments — Air  Starting  Systems — Electric  Starting — Bat- 
tery Ignition 457-571 

INDEX  .  573 


AVIATION  ENGINES 

DESIGN— CONSTRUCTION—  REPAIR 

CHAPTER  I 

Brief  Consideration  of  Aircraft  Types — Essential  Requirements  of 
Aerial  Motors — Aviation  Engines  Must  Be  Light — Factors  In- 
fluencing Power  Needed — Why  Explosive  Motors  Are.  Best — His- 
torical— Main  Types  of  Internal  Combustion  Engines. 

BRIEF   CONSIDERATION   OF  AIRCRAFT  TYPES 

THE  conquest  of  the  air  is  one  of  the  most  stupendous 
achievements  of  the  ages.  Human  flight  opens  the  sky 
to  man  as  a  new  road,  and  because  it  is  a  road  free  of  all 
obstructions  and  leads  everywhere,  affording  the  shortest 
distance  to  any  place,  it  offers  to  man  the  prospect  of 
unlimited  freedom.  The  aircraft  promises  to  span  con- 
tinents like  railroads,  to  bridge  seas  like  ships,  to  go  over 
mountains  and  forests  like  birds,  and  to  quicken  and 
simplify  the  problems  of  transportation.  While  the  actual 
conquest  of  the  air  is  an  accomplishment  just  being  real- 
ized in  our  days,  the  idea  and  yearning  to  conquer  the  air 
are  old,  possibly  as  old  as  intellect  itself.  The  myths  of 
different  races  tell  of  winged  gods  and  flying  men,  and 
show  that  for  ages  to  fly  was  the  highest  conception  of 
the  sublime.  No  other  agent  is  more  responsible  for  sus- 
tained flight  than  the  internal  combustion  motor,  and  it 
was  only  when  this  form  of  prime  mover  had  been  fully 
developed  that  it  was  possible  for  man  to  leave  the  ground 
and  alight  at  will,  not  depending  upon  the  caprices  of 
the  winds  or  lifting  power  of  gases  as  with  the  balloon. 
It  is  safe  to  say  that  the  solution  of  the  problem  of  flight 
would  have  been  attained  many  years  ago  if  the  proper 
source  of  power  had  been  available  as  all  the  essential 

17 


18  Aviation  Engines 

elements  of  the  modern  aeroplane  and  dirigible  balloon, 
other  than  the  power  plant,  were  known  to  early  philoso- 
phers and  scientists. 

Aeronautics  is  divided  into  two  fundamentally  differ- 
ent branches — aviatics  and  aerostatics.  The  first  com- 
prises all  types  of  aeroplanes  and  heavier  than  air  flying 
machines  such  as  the  helicopters,  kites,  etc. ;  the  second 
includes  dirigible  balloons,  passive  balloons  and  all  craft 
which  rise  in  the  air  by  utilizing  the  lifting  force  of  gases. 
Aeroplanes  are  the  only  practical  form  of  heavier-than-air 
machines,  as  the  helicopters  (machines  intended  to  be 
lifted  directly  into  the  air  by  propellers,  without  the  sus- 
taining effect  of  planes),  and  ornithopters,  or  flapping 
wing  types,  have  not  been  thoroughly  developed,  and  in 
fact,  there  are  so  many  serious  mechanical  problems  to 
be  solved  before  either  of  these  types  of  air '  craft  will 
function  properly  that  experts  express  grave  doubts  re- 
garding the  practicability  of  either.  Aeroplanes  are  di- 
vided into  two  main  types — monoplanes  or  single  surface 
forms,  and  bi-planes  or  machines  having  two  sets  of  lift- 
ing surfaces,  one  suspended  over  the  other.  A  third  type, 
.  the  triplane,  is  not  very  widely  used. 

Dirigible  balloons  are  divided  into  three  classes:  the 
rigid,  the  semi-rigid,  and  the  non-rigid.  The  rigid  has  a 
frame  or  skeleton  of  either  wood  or  metal  inside  of  the 
bag,  to  stiffen  it;  the  semi-rigid  is  reinforced  by  a  wire 
net  and  metal  attachments;  while  the  non-rigid  is  just  a 
bag  filled  with  gas.  The  aeroplane,  more  than  the  dirigible 
and  balloon,  stands  as  the  emblem  of  the  conquest  of  the 
air.  Two  reasons  for  this  are  that  power  flight  is  a  real 
conquest  of  the  air,  a  real  victory  over  the  battling  ele- 
ments ;  secondly,  because  the  aeroplane,  or  any  flying  ma- 
chine that  may  follow,  brings  air  travel  within  the  reach 
of  everybody.  In  practical  development,  the  dirigible  may 
be  the  steamship  of  the  air,  which  will  render  invaluable 
services  of  a  certain  kind,  and  the  aeroplane  will  be  the 
automobile  of  the  air,  to  be  used  by  the  multitude,  perhaps 
for  as  many  purposes  as  the  automobile  is  now  being  used. 


Aviation  Motor  Requirements  19 

ESSENTIAL   REQUIREMENTS    OF    AERIAL    MOTORS 

One  of  the  marked  features  of  aircraft  development  has 
been  the  effect  it  has  had  upon  the  refinement  and  perfec- 
tion of  the  internal  combustion  motor.  Without  question 
gasoline-motors  intended  for  aircraft  are  the  nearest  to 
perfection  of  any  other  type  yet  evolved.  Because  of  the 
peculiar  demands  imposed  upon  the  aeronautical  motor  it 
must  possess  all  the  features  of  reliability,  economy  and 
efficiency  now  present  with  automobile  or  marine  engines 
and  then  must  have  distinctive  points  of  its  own.  Owing 
to  the  unstable  nature  of  the  medium  through  which  it  is 
operated  and  the  fact  that  heavier-than-air  machines  can 
maintain  flight  only  as  long  as  the  power  plant  is  func- 
tioning properly,  an  airship  motor  must  be  more  reliable 
than  any  used  on  either  land  or  water.  While  a  few 
pounds  of  metal  more  or  less  makes  practically  no  dif- 
ference in  a  marine  motor  and  has  very  little  effect  upon 
the  speed  or  hill-climbing  ability. of  an  automobile,  an 
airship  motor  must  be  as  light  as  it  is  possible  to  make 
it  because  every  pound  counts,  whether  the  motor  is  to  be 
fitted  into  an  aeroplane  or  in  a  dirigible  balloon. 

Airship  motors,  as  a  rule,  must  operate  constantly  at 
high  speeds  in  order  to  obtain  a  maximum  power  delivery 
with  a  minimum  piston  displacement.  In  automobiles,  or 
motor  boats,  motors  are  not  required  to  run  constantly  at 
their  maximum  speed.  Most  aircraft  motors  must  func- 
tion for  extended  periods  at  speed  as  nearly  the  maximum 
as  possible.  Another  thing  that  militates  against  the  air- 
craft motor  is  the  more  or  less  unsteady  foundation  to 
which  it  is  attached.  The  necessarily  light  framework  of  the 
aeroplane  makes  it  hard  for  a  motor  to  perform  at  maxi- 
mum efficiency  on  account  of  the  vibration  of  its  foundation 
while  the  craft  is  in  flight.  Marine  and  motor  car  engines, 
while  not  placed  on  foundations  as  firm  as  those  provided 
for  stationary  power  plants,  are  installed  on  bases  of  much 
more  stability  than  the  light  structure  of  an  aeroplane. 
The  aircraft  motor,  therefore,  must  be  balanced  to  a  nicety 


20  Aviation  Engines 

and  must  run  steadily  under  the  most  unfavorable  con- 
ditions. 

AERIAL  MOTORS  MUST  BE  LIGHT 

The  capacity  of  light  motors  designed  for  aerial  work 
per  unit  of  mass  is  surprising  to  those  not  fully  con- 
versant with  the  possibilities  that  a  thorough  knowledge 
of  proportions  of  parts  and  the  use  of  special  metals 
developed  by  the  automobile  industry  make  possible.  Ac- 
tivity in  the  development  of  light  motors  has  been  more 
pronounced  in  France  than  in  any  other  country.  Some 
of  these  motors  have  been  complicated  types  made  light 
by  the  skillful  proportioning  of  parts,  others  are  of  the 
refined  simpler  form  modified  from  current  automobile 
practice.  There  is  a  tendency  to  depart  from  the  freakish 
or  unconventional  construction  and  to  adhere  more  closely 
to  standard  forms  because  it  is  necessary  to  have  the  parts 
of  such  size  that  every  quality  making  for  reliability, 
efficiency  and  endurance  are  incorporated  in  the  design. 
Aeroplane  motors  range  from  two  cylinders  to  forms  hav- 
ing fourteen  and  sixteen  cylinders  and  the  arrangement 
of  these  members  varies  from  the  conventional  vertical 
tandem  and  opposed  placing  to  the  V  form  or  the  more 
unusual  radial  motors  having  either  fixed ^ or  rotary  cyl- 
inders. The  weight  has  been  reduced  so  ft*  is  possible  to 
obtain  a  complete  power  plant  of  the  revolving  cylinder 
air-cooled  type  that  will  not  weigh  more  than  three  pounds 
per  actual  horse-power  and  in  some  cases  less  than  this. 

If  we  give  brief  consideration  to  the  requirements  of 
the  aviator  it  will  be  evident  that  one  of  the  most  im- 
portant is  securing  maximum  power  with  minimum  mass, 
and  it  is  desirable  to  conserve  all  of  the  good  qualities 
existing  in  standard  automobile  motors.  These  are  cer- 
tainty of  operation,  good  mechanical  balance  and  uniform 
delivery  of  power — fundamental  conditions  which  must  be 
attained  before  a  power  plant  can  be  considered  practical. 
There  are  in  addition,  secondary  considerations,  none  the 
less  desirable,  if  not  absolutely  essential.  These  are  min- 


Factors  Influencing  Power  Needed  21 

imum  consumption  of  fuel  and  lubricating  oil,  which  is 
really  a  factor  of  import,  for  upon  the  economy  depends 
the  capacity  and  flying  radius.  As  the  amount  of  liquid 
fuel  must  be  limited  the  most  suitable  motor  will  be  that 
which  is  powerful  and  at  the  same  time  economical.  An- 
other important  feature  is  to  secure  accessibility  of  com- 
ponents in  order  to  make  easy  repair  or  adjustment  of 
parts  possible.  It  is  possible  to  obtain  sufficiently  light- 
weight motors  without  radical  departure  from  established 
practice.  Water-cooled  power  plants  have  been  designed 
that  will  wTeigh  but  four  or  five  pounds  per  horse-power 
and  in  these  forms  we  have  a  practical  power  plant 
capable  of  extended  operation. 

FACTORS  INFLUENCING  POWER   NEEDED 

Work  is  performed  whenever  an  object  is  moved  against 
a  resistance,  and  the  amount  of  work  performed  depends 
not  only  on  the  amount  of  resistance  overcome  but  also 
upon  the  amount  of  time  utilized  in  accomplishing  a  given 
task.  Work  is  measured  in  horse-power  for  convenience. 
It  will  take  one  horse-power  to  move  33,000  pounds  one 
foot  in  one  minute  or  550  pounds  one  foot  in  one  second. 
The  same  work  would  be  done  if  330  pounds  were  moved 
100  feet  in  one  ^  minute.  It  requires  a  definite  amount  of 
power  to  move  a  vehicle  over  the  ground  at  a  certain 
speed,  so  it  must  take  power  to  overcome  resistance  of 
an  airplane  in  the  air.  Disregarding  the  factor  of  air 
density,  it  will  take  more  power  as  the  speed  increases 
if  the  weight  or  resistance  remains  constant,  or  more 
power  if  the  speed  remains  constant  and  the  resistance 
increases.  The  airplane  is  supported  by  air  reaction  un- 
der the  planes  or  lifting  surfaces  and  the  value  of  this 
reaction  depends  upon  the  shape  of  the  aerofoil,  the 
amount  it  is  tilted  and  the  speed  at  which  it  is  drawn 
through  the  air.  The  angle  of  incidence  or  degree  of 
wing  tilt  regulates  the  power  required  to  a  certain  degree 
as  this  affects  the  speed  of  horizontal  flight  as  well  as  the 
resistance.  Eesistance  may  be  of  two  kinds,  one  that  is 


22  Aviation  Engines 

necessary  and  the  other  that  it  is  desirable  to  reduce  to 
the  lowest  point  possible.  There  is  the  wing  resistance 
and  the  sum  of  the  resistances  of  the  rest  of  the  machine 
such  as  fuselage,  struts,  wires,  landing  gear,  etc.  If  we 
assume  that  a  certain  airplane  offered  a  total  resistance 
of  300  pounds  and  we  wished  to  drive  it  through  the  air 
at  a  speed  of  sixty  miles  per  hour,  we  can  find  the  horse- 
power needed  by  a  very  simple  computation  as  follows : 
The  product  of 

300  pounds  resistance  times  speed  of  88  feet 
•  per  second  times  60  seconds  in  a  minute 

-  =  H.P.  needed, 
divided  by  33,000  foot  pounds  per  minute 

in  one  horse-power 

The  result  is  the  horse-power  needed,  or 

300  X  88  X  60 

=  48  H.P. 

33,000 

Just  as  it  takes  more  power  to  climb  a  hill  than  it  does 
to  run  a  car  on  the  level,  it  takes  more  power  to  climb 
in  the  air  with  an  airplane  than  it  does  to  fly  on  the  level. 
The  more  rapid  the  climb,  the  more  power  it  will  take. 
If  the  resistance  remains  300  pounds  and  it  is  necessary 
to  drive  the  plane  at  90  miles  per  hour,  we  merely  sub- 
stitute proper  values  in  the  above  formula  and  we  have 

300  pounds  times  132  feet  per  second  times  60 
seconds  in  a  minute 

rrc\     TT  T> 

33,000  foot  pounds  per  minute  in  one 
horse-power 

The  same  results  can  be  obtained  by  dividing  the  product 
of  the  resistance  in  pounds  times  speed  in  feet  per  second 
by  550,  which  is  the  foot-pounds  of  work  done  in  one 
second  to  equal  one  horse-power.  Naturally,  the  amount 
of  propeller  thrust  measured  in  pounds  necessary  to  drive 
an  airplane  must  be  greater  than  the  resistance  by  a  sub- 
stantial margin  if  the  plane  is  to  fly  and  climb  as  well. 


Computations  for  Horse-Power  Needed 


23 


The  following  formulae  were  given  in  "The  Aeroplane" 
of  London  and  can  be  used  to  advantage  by  those  desiring 
to  make  computations  to  ascertain  power  requirements: 
The  thrust  of  the  propeller  depends  on  the  power  of 


L=  Lift  =  Weighl  =  W 

D  =  Drift 

R=  Reaction 

Angle  of  Incidence 


Pr-  Momentum-  M 

Pr  2  Jt  =  Work 

Pr  2  31=  WorkMln. 


B 


'.P.  or  in  English 
Pr27CR 


33.000 


-H.P. 


2rJt 


Fig.  1. — Diagrams  Illustrating  Computations  for  Horse-Power  Required  for 

Airplane  Flight. 


24  Aviation  Engines 

the  motor,  and  on  the  diameter  and  pitch  of  the  propeller. 
If  the  required  thrust  to  a  certain  machine  is  known,  the 
calculation  for  the  horse-power  of  the  motor  should  be  an 
easy  matter. 

The  required  thrust  is  the  sum  of  three  different  "  re- 
sistances. "  The  first  is  the  ' 'drift "  (dynamical  head  re- 
sistance of  the  aerofoils),  i.e.,  tan  a  x  lift  (L),  lift  being 
equal  to  the  total  weight  of  machine  (W)  for  horizontal 
flight  and  «  equal  to  the  angle  of  incidence.  Certainly  we 
must  take  the  tan  a  at  the  maximum  Kv  value  for  minimum 
speed,  as  then  the  drift  is  the  greatest  (Fig.  1,  A). 

Another  method  for  finding  the  drift  is  D  —  K  X  AV2, 
when  we  take  the  drift  again  so  as  to  be  greatest. 

The  second  " resistance "  is  the  total  head  resistance 
of  the  machine,  at  its  maximum  velocity.  And  the  third 
is  the  thrust  for  climbing.  The  horse-power  for  climbing 
can  be  found  out  in  two  different  ways.  I  first  propose 
to  deal  with  the  method,  where  we  find  out  the  actual 
horse-power  wanted  for  a  certain  climbing  speed  to  our 
machine,  where 

climbing  speed/sec.  X  W 

H.P.  = 

550 

In  this  case  we  know  already  the  horse-power  for  climb- 
ing, and  we  can  proceed  with  our  calculation. 

With  the  other  method  we  shall  find  out  the  "thrust" 
in  pounds  or  kilograms  wanted  for  climbing  and  add  it 
to  drift  and  total  head  resistance,  and  we  shall  have  the 
total  "  thrust "  of  our  machine  and  we  shall  denote  it 
with  T,  while  thrust  for  climbing  shall  be  Tc. 

The  following  calculation  is  at  our  service  to  find  out 

VcXW 

this  thrust  for  climbing —  H.P., 

550 

H.P.  X  550 

thence  Vc  = (1) 

W 


Computations  for  Horse-Power  Needed  25 

To  XV 

H.P.  =  -  -  ,  then  from 
550 

To  XV 
-  X550 

550  To  XV  VcXW 

(1)  Vc  =  -  =  -  -  ,  thence,  Tc  =  - 
W  W  V 

Whether  T  means  drifts,  head  resistance  and  thrust 
for  climbing,  or  drift  and  head  resistance  only,  the  fol- 
lowing calculation  is  the  same,  only  in  the  latter  case,  of 
course,  we  must  add  the  horse-power  required  for  climb- 
ing to  the  result  to  obtain  the  total  horse-power. 

Now,  when  we  know  the  total  thrust,  we  shall  find  the 
horse-power  in  the  following  manner: 

Pr2*R 

We  know  that  the  H.P.  =  -  in  kilograms,  or  in 

75X60 


•English  measure,  H.P.  =  -  (Fig.  1,  B) 

33,000 

where  P  =  pressure  in  klgs.  or  Ibs. 

r  =  radius  on  which  P  is  acting. 
R  =  Revolution/min. 

M.R.  2  w 

When  B  X  r  =  M,  then  H.P.  =  -  ,  thence, 

4,500 

H.P.  X  4,500      716.2  H.P. 

M  =  -          -  =  -  -  in  meter  kilograms, 
R2*  R 

H.P.  33,000      5253.1  H.P. 
or  in  English  system  M  =  —  -  in  foot 

R2*  R 

pounds. 

Now  the  power  on  the  circumference  of  the  propeller 

M 
will  be  reduced  by  its  radius,  so  it  will  be  —  —  p.    A  part 


26  Aviation  Engines 

of  p  will  be  used  for  counteracting  the  air  and  bearing  fric- 
tion, so  that  the  total  power  on  the  circumference  of  the 

M 

propeller  will  be  —  X  *»)  =  P  where   rj  is  the  mechanical 
r 

fi 
efficiency  of  the  propeller.  Now  -      -  =  T,  where  a  is  taken 

tan  <x 

on  the  tip  of  the  propeller. 

I  take  a  at  the  tip,  but  it  can  be  taken,  of  course,  at  any 

M 

point,  but  then  in  equation  p  =  —  ,  r  must  be  taken  only  up 

r 

to  this  point,  and  not  the  whole  radius  ;  but  it  is  more  corn- 

Pitch 
fortable  to  take  it  at  the  tip,  as  tan  a  =  —     -  (Fig.  1,  C). 

r2?u 

Now  we  can  write  up  the  equation  of  the  thrust  : 

716.2  H.P.  rj  5253.1  H.P.  YJ 

T  =  -  -  ,  or  in  English  measure 


R  r  tan  a  R  r  tan  a 

T  X  R  X  r  tan  a 

thence  H.P.  =  -  ,  or  in  English  measure 
716.2  r] 

T  X  R  X  r  tan  a 


5253.1  r] 

The  computations  and  formulae  given  are  of  most  value 
to  the  student  engineer  rather  than  matters  of  general 
interest,  but  are  given  so  that  a  general  idea  may  be 
secured  of  how  airplane  design  influences  power  needed 
to  secure  sustained  flight.  It  will  be  apparent  that  the 
resistance  of  an  airplane  depends  upon  numerous  con- 
siderations of  design  which  require  considerable  research 
in  aerodynamics  to  determine  accurately.  It  is  obvious 
that  the  more  resistance  there  is,  the  more  power  needed 
to  fly  at  a  given  speed.  Light  monoplanes  have  been 
flown  with  as  little  as  15  horse-power  for  short  distances, 


Why  Explosive  Motors  Are  Best  27 

but  most  planes  now  built  use  engines  of  100  horse-power 
or  more.  Giant  airplanes  have  been  constructed  having 
2,000  horse-power  distributed  in  four  power  units.  The 
amount  of  power  provided  for  an  airplane  of  given  design 
varies  widely  as  many  conditions  govern  this,  but  it  will 
range  from  approximately  one  horse-power  to  each  8 
pounds  weight  in  the  case  of  very  light,  fast  machines 
to  one  horse-power  to  15  or  18  pounds  of  the  total  weight 
in  the  case  of  medium  speed  machines.  The  development 
in  airplane  and  power  plant  design  is  so  rapid,  however, 
that  the  figures  given  can  be  considered  only  in  the  light 
of  general  averages  rather  than  being  typical  of  current 
practice. 

WHY  EXPLOSIVE   MOTOKS   ARE   BEST 

Internal  combustion  engines  are  best  for  airplanes  "and 
all  types  of  aircraft  for  the  same  reasons  that  they  are 
universally  used  as  a  source  of  power  for  automobiles. 
The  gasoline  engine  is  the  lightest  known  form  of  prime 
mover  and  a  more  efficient  one  than  a  steam  engine,  es- 
pecially in  the  small  powers  used  for  airplane  propul- 
sion. It  has  been  stated  that  by  very  careful  designing 
a  steam  plant  and  engine  could  be  made  that  would  be 
practical  for  airplane  propulsion,  but  even  with  the  latest 
development  it  is  doubtful  if  steam  power  can  be  utilized 
in  aircraft  to  as  good  advantage  as  modern  gasoline- 
engines  are.  While  the  steam-engine  is  considered  very 
much  simpler  than  a  gas-motor,  the  latter  is  much  more 
easily  mastered  by  the  non-technical  aviator  and  certainly 
requires  less  attention.  A  weight  of  10  pounds  per  horse- 
power is  possible  in  a  condensing  steam  plant  but  this 
figure  is  nearly  double  or  triple  what  is  easily  secured 
with  a  gas-motor  which  may  weigh  but  5  pounds  per  horse- 
power in  the  water  cooled  forms  and  but  2  or  3  pounds 
in  the  air-cooled  types.  The  fuel  consumption  is  twice 
as  great  in  a  -steam-power  plant  (owing  to  heat  losses) 
as  would  be  the  case  in  a  gasoline  engine  of  equal  power 
and  much  IP.SS  weight. 


28  Aviation  Engines 

The  internal-combustion  engine  has  come  seemingly 
like  an  avalanche  of  a  decade;  but  it  has  come  to  stay, 
to  take  its  well-deserved  position  among  the  powers  for 
aiding  labor.  Its  ready  adaptation  to  road,  aerial  and 
marine  service  has  made  it  a  wonder  of  the  age  in  the 
development  of  speed  not  before  dreamed  of  as  a  possi- 
bility; yet  in  so  short  a  time,  its  power  for  speed  has 
taken  rank  on  the  common  road  against  the  locomotive 
on  the  rail  with  its  century's  progress.  It  has  made  aerial 
navigation  possible  and  practical,  it  furnishes  power  for 
all  marine  craft  from  the  light  canoe  to.  the  transatlantic 
liner.  It  operates  the  machine  tools  of  the  mechanic,  tills 
the  soil  for  the  farmer  and  provides  healthful  recreation 
for  thousands  by  furnishing  an  economical  means  of  trans- 
port by  land  and  sea.  It  has  been  a  universal  mechanical 
education  for  the  masses,  and  in  its  present  forms  repre- 
sents the  great  refinement  and  development  made  possible 
by  the  concentration  of  the  world's  master  minds  on  the 
problems  incidental  to  internal  combustion  engineering. 

HISTOKICAL 

Although  the  ideal  principle  of  explosive  power  was 
conceived  some  two  hundred  years  ago,  at  which  time 
--experiments' were  made  with  gunpowder  as  the  explosive 
element,  it  was  not  until  the  last  years  of  the  eighteenth 
century  that  the  idea  took  a  patentable  shape,  and  not 
until  about  1826  (Brown's  gas- vacuum  engine)  that  a  fur- 
ther progress  was  made  in  England  by  condensing  the 
products  of  combustion  by  a  jet  of  water,  thus  creating 
a  partial  vacuum. 

Brown's  was  probably  the  first  explosive  engine  that 
did  real  work.  It  was  clumsy  and  unwieldy  and  was  soon 
relegated  to  its  place  among  the  failures  of  previous  ex- 
periments. No  approach  to  active  explosive  effect  in  a 
cylinder  was  reached  in  practice,  although  many  ingenious 
designs  were  described,  until  about  1838  and  the  following 
years.  Barnett's  engine  in  England  was  the  first  attempt 
to  compress  the  charge  before  exploding.  From  this  ^Ime 


Why  Explosive  Motors  Are  Best  29 

on  to  about  1860  many  patents  were  issued  in  Europe  and 
a  few  in  the  United  States  for  gas-engines,  but  the  prog- 
ress was  .slow,  and  its  practical  introduction  for  power 
came  with  spasmodic  effect  and  low  efficiency.  From  1860 
on,  practical  improvement  seems  to  have  been  made,  and 
the  Lenoir  motor  was  produced  in  France  and  brought 
to  the  United  States.  It  failed  to  meet  expectations,  and 
was  soon  followed  by  further  improvements  in  the  Hugon 
motor  in  France  (1862),  followed  by  Beau  de  Rocha's 
four-cycle  idea,  which  has  been  slowly  developed  through 
a  long  series  of  experimental  trials  by  different  inventors. 
In  the  hands  of  Otto  and  Langdon  a  further  progress  was 
made,  and  numerous  patents  were  issued  in  England, 
France,  and  Germany,  and  followed  up  by  an  increasing 
interest  in  the  United  States,  with  a  few  patents. 

From  1870  improvements  seem  to  have  advanced  at 
a  steady  rate,  and  largely  in  the  valve-gear  and  precision 
of  governing  for  variable  load.  The  early  idea  of  the  ne- 
cessity of  slow  combustion  was  a  great  drawback  in  the 
advancement  of  efficiency,  and  the  suggestion  of  de  Eocha 
in  1862  did  not  take  root  as  a  prophetic  truth  until  many 
failures  and  years  of  experience  had  taught  the  funda- 
mental axiom  that  rapidity  of  action  in  both  combustion 
and  expansion  was  the  basis  of  success  in  explosive  motors. 

With  this  truth  and  the  demand  for  small  and  safe 
prime  movers,  the  manufacture  of  gas-engines  increased 
in  Europe  and  America  at  a  more  rapid  rate,  and  improve- 
ments in  perfecting  the  details  of  this  cheap  and  efficient 
prime  mover  have  finally  raised  it  to  the  dignity  of  a 
standard  motor  and  a  dangerous  rival  of  the  steam-engine 
for  small  and  intermediate  powers,  with  a  prospect  of 
largely  increasing  its  individual  units  to  many  hundred, 
if  not  to  the  thousand  horse-power  in  a  single  cylinder. 
The  unit  size  in  a  single  cylinder  has  now  reached  to  about 
700  horse-power  and  by  combining  cylinders  in  the  same 
machine,  powers  of  from  1,500  to  2,000  horse-power  are 
now  available  for  large  power-plants. 


30  Aviation  Engines 

MAIN     TYPES    OF    INTERNAL-COMBUSTION     ENGINES 

This  form  of  prime  mover  has  been  built  in  so  many 
different  types,  all  of  which  have  operated  with  some 
degree  of  success  that  the  diversity  in  form  will  not  be 
generally  appreciated  unless  some  attempt  is  made  to 
classify  the  various  designs  that  have  received  practical 
application.  Obviously  the  same  type  of  engine  is  not 
universally  applicable,  because  each  class  of  work  has 
individual  peculiarities  which  can  best  be  met  by  an  en- 
gine designed  with  the  peculiar  conditions  present  in  view. 
The  following  tabular  synopsis  will  enable  the  reader  to 
judge  the  extent  of  the  development  of  what  is  now  the 
most  popular  prime  mover  for  all  purposes. 

A.      Internal  Combustion  (Standard  Type) 

1.  Single  Acting  (Standard  Type) 

2.  Double  Acting  (For  Large  Power  Only) 
,  3.     Simple   (Universal  Form) 

4.  Compound  (Barely  Used) 

5.  Eeciprocating  Piston  (Standard  Type) 

6.  Turbine    (Revolving  Eotor,  not  fully  devel- 

oped) 

Al.     Two-Stroke  Cycle 

a.  Two  Port 

b.  Three  Port 

c.  Combined  Two  and  Three  Port 

d.  Fourth  Port  Accelerator 

e.  Differential  Piston  Type 

f.  Distributor  Valve  System 

A2.    Four-Stroke  Cycle 

a.  Automatic  Inlet  Valve 

b.  Mechanical  Inlet  Valve 

c.  Poppet  or  Mushroom  Valve 

d.  Slide  Valve 

d  1.     Sleeve  Valve 

d  2.     Eeciprocating  Eing  Valve 

d  3.     Piston  Valve 


Gas  Engine  Types  Classified  31 

e.  Eotary  Valves 

e  1.    Disc 

e  2.     Cylinder  or  Barrel 

e  3.     Single  Cone 

e  4.     Double  Cone 

f.  Two  Piston  (Balanced  Explosion) 

g.  Eotary. Cylinder,  Fixed  Crank  (Aerial) 

h.     Fixed  Cylinder,  Eotary  Crank  (Standard 
Type) 

A3.     Six-Stroke  Cycle 

B.      External  Combustion  (Practically  Obsolete) 

a.  Turbine,  Eevolving  Eotor 

b.  Eeciprocating  Piston 

CLASSIFICATION   BY   CYLINDER  ARRANGEMENT 

Single  Cylinder 

a.  Vertical 

b.  Horizontal 

c.  Inverted  Vertical 

Double  Cylinder 

a.  Vertical 

b.  Horizontal  (Side  by  Side) 

c.  Horizontal  (Opposed) 

d.  45  to  90  Degrees  V  (Angularly  Disposed) 

e.  Horizontal  Tandem  (Double  Acting) 

Three  Cylinder 

a.  Vertical 

b.  Horizontal 

c.  Eotary  (Cylinders  Spaced  at  120  Degrees) 

d.  Eadially  Placed  (Stationary  Cylinders) 

e.  One  Vertical,  One  Each  Side  at  an  Angle 

f.  Compound    (Two  High  Pressure,  One  Low 

Pressure) 

Four  Cylinder 

a.  Vertical 

b.  Horizontal  (Side  by  Side) 


32  Aviation  Engines 

c.  Horizontal  (Two  Pairs  Opposed) 

d.  45  to  90  Degrees  V 

e.  Twin  Tandem  (Double  Acting) 

Five  Cylinder 

a.  Vertical  (Five  Throw  Crankshaft) 

b.  Eadially  Spaced  at  72  Degrees  (Stationary) 

c.  Eadially  Placed  Above  Crankshaft  ( Station- 

ary) 

d.  Placed  Around  Rotary  Crankcase  (72  Degrees 

Spacing) 

Six  Cylinder 

a.  Vertical 

b.  Horizontal  (Three  Pairs  Opposed) 

c.  45  to  90  Degrees  V 

Seven  Cylinder 

a.     Equally  Spaced  (Eotary) 

Eight  Cylinder 

a.  Vertical 

b.  Horizontal  (Four  Pairs  Opposed) 

c.  45  to  90  Degrees  V 

Nine  Cylinder 
.   a.     Equally  Spaced  (Eotary) 

Twelve  Cylinder 

a.  Vertical 

b.  Horizontal  (Six  Pairs  Opposed) 

c.  45  to  90  Degrees  V 

Fourteen  Cylinder 
a.     Eotary 

Sixteen  Cylinder 

a.  45  to  90  Degrees  V 

b.  Horizontal  (Eight  Pairs  Opposed) 

Eighteen  Cylinder 
a.     Eotary  Cylinder 


Two-  Cylinder,  Double  Acting/Four  Cycle  Engine  for  Blast  Furnace  Gas  Fuel 

Weight  600  Pounds  per  Horsepower 
Very  slow  speed,  made  in  siz.es  uptb  2000  Horsepower.  60io  100  R.P.M. 


Two  Cylinder  Opposed  Gas  Engine  - 150  to  650  Horsepower  Sizes. 
500  to  600   Pounds  per  Horsepower.     90  to  100  R.P.M. 


Stationary  Diesel  Engine    s      d          Stationary  Gas  Engine 
450  to  500  Pounds  per        Approximately        Four  Cycle -Two  Cylinder 
Horsepower  200  R.P.M.          500  Pounds  per  Horsepower 


Fig.  2. — Plate  Showing  Heavy,  Slow  Speed  Internal  Combustion  Engines 
Used  Only  for  Stationary  Power  in  Large  Installations  Giving  Weight 
to  Horse-Power  Ratio. 

33 


Four  Cylinder  Diesel  Engine  for  Marine  Use 
250    Pounds  perHorsepower 


Two- Cycle  Marine  Engine 
50-100  Pounds  per  Horsepower 
600to  800   R.P  M. 


Single  Cylinder  Vertical  Farm  Engine 
150  Pounds  per  Horsepower-  Speed  400  R  RM. 


Two  Cylinder  Four  Cycle  Tractor  Engine 
15  Pounds  per  Horsepower 
800  to  1000.  R.P.M  . 


Four -Cylinder  Four  Cycle  Automobile  PowerPlant: 
Weiqhsabout  ZS  Pounds  per  Horsepower 
IZOO  to  ZOOO   R.P.  M. 


Pig.  3. Various  Forms  of  Internal  Combustion  Engines  Showing  Decrease 

in  Weight  to  Horse-Power  Ratio  with  Augmenting  Speed  of  Rotation. 

34    , 


Eight  Cylmder"Vee"Au+onnobile  Engine 
15  to  18  Pounds  per  Horse  power 
Speeds  1500  toZOOOR  P.M. 


Two  Cylinder-AirCooled  Motorcycle 

Engine  weighH  8MO  Pounds  Horsepower 

Speed  3000  R. P.M. 


Six,  Eight  or  Twelve  Cylinder  Water  Cooled  Aviation  Engine,  Tandem  or  V  Form 

4  to  6  Pounds  per  Horsepower 
Speed  1500  R,R  M.  Direct  Coupled  -  2000  R  RM.Geared'Drive 


Seven  or  Nine  Cylinder  Revolving 

Air  Cooled 
Speed  1200  R.RM.2.8Pounds  perHorsepowsr 


Fourteen  or  Eighteen  Cylinder 
Revolving  Air  Cooled  Aviation  Engine 

.   Speed  1200  R.P.M. 
2  Pounds  per  Horsepower 


Fig.  4. — Internal  Combustion  Engine  Types  of  Extremely  Fine  Construction 
and  Kefined  Design,  Showing  Great  Power  Outputs  for  Very  Small 
Weighty  a  Feature  Very  Much  Desired  in  Airplane  Power  Plants. 

35 


#6  Aviation  Engines 

Of  all  the  types  enumerated  above  engines  having  less 
than  eight  cylinders  are  the  most  popular  in  everything 
but  aircraft  work.  The  four-cylinder  vertical  is  without 
doubt  the  most  widely  used  of  all  types  owing  to  the 
large  number  employed  as  automobile  power  plants. 
Stationary  engines  in  small  and  medium  powers  are  in- 
variably of  the  single  or  double  form.  Three-cylinder 
engines  are  seldom,  used  at  the  present  time,  except  in 
marine  work  and  in  some  stationary  forms.  Eight-  and 
twelve-cylinder  motors  have  received  but  limited  appli- 
cation and  practically  always  in  automobiles,  racing  motor 
boats  or  in  aircraft.'  The  only  example  of  a  fourteen- 
cylinder  motor  to  be  used  to  any  extent  is  incorporated 
in  aeroplane  construction.  This  is  also  true  of  the  six- 
teen- and  eighteen-cylinder  forms  and  of  twenty-four- 
cylinder  engines  now  in  process  of  development. 

The  duty  an  engine  is  designed  for  determines  the 
weight  per  horse-power.  High  powered  engines  intended 
for  steady  service  are  always  of  the  slow  speed  type  and 
consequently  are  of  very  massive  construction.  Various 
forms  of  heavy  duty  type  stationary  engines  are  shown 
at  Fig.  2.  Some  of  these  engines  may  weigh  as  much  as 
600  pounds  per  horse-power.  A  further  study  is  possible 
by  consulting  data  given  on  Figs.  3  and  4.  As  the  crank- 
shaft speed  increases  and  cylinders  are  multiplied  the 
engines  become  lighter.  While  the  big  stationary  power 
plants  may  run  for  years  without  attention,  airplane  en- 
gines require  rebuilding  after  about  60  to  80  hours  air 
service  for  the  fixed  cylinder  types  and  40  hours  or  less 
for  the  rotary  cylinder  air-cooled  forms.  There  is  evi- 
dently a  decrease  in  durability  and  reliability  as  the 
weight  is  lessened.  These  illustrations  also  permit  of 
obtaining  a  good  idea  of  the  variety  of  forms  internal 
combustion  engines  are  made  in. 


CHAPTER  II 

Operating  Principles  of  Two-  and  Four-Stroke  Engines — Four-cycle 
Action — Two-cycle  Action — Comparing  Two-  and  Four-cycle  Types 
— Theory  of  Gas  and  Gasoline  Engine — Early  Gas-Engine  Forms — 
Isothermal  Law — Adiabatic  Law — Temperature  Computations — 
Heat  and  Its  Work — Conversion  of  Heat  to  Power — Requisites 
for  Best  Power  Effect. 

OPERATING   PRINCIPLES   OF    TWO-   AND    FOUR-STROKE 
CYCLE  ENGINES 

BEFORE  discussing  the  construction  of  the  various  forms 
of  internal  combustion  engines  it  may  be  well  to  describe 
the  operating  cycle  of  the  types  most  generally  used. 
The  two-cycle  engine  is  the  simplest  because  there  are  no 
valves  in  connection  with  the  cylinder,  as  the  gas  is  in- 
troduced into  that  member  and  expelled  from  it  through 
ports  cored  into  the  cylinder  walls.  These  are  covered  by 
the  piston  at  a  certain  portion  of  its  travel  and  uncov- 
ered at  other  parts  of  its  stroke.  In  the  four-cycle  engine 
the  explosive  gas  is  admitted  to  the  cylinder  through  a 
port  at  the  head  end  closed  by  a  valve,  while  the  exhaust 
gas  is  expelled  through  another  port  controlled  in  a  simi- 
lar manner.  These  valves  are  operated  by  mechanism 
distinct  from  the  piston. 

The  action  of  the  four-cycle  type  may  be  easily  under- 
stood if  one  refers  to  illustrations  at  Figs.  5  and  6.  It 
is  called  the  "four-stroke  engine"  because  the  piston  must 
make  four  strokes  in  the  cylinder  for  each  explosion  or 
power  impulse  obtained.  The  principle  of  the  gas-engine 
of  the  internal  combustion  type  is  similar  to  that  of  a 
gun,  i.e.,  power  is  obtained  by  the  rapid  combustion  of 
some  explosive  or  other  quick  burning  substance.  The 
bullet  is  driven  out  of  the  gun  barrel  by  the  pressure  of 
the  gas  evolved  when  the  charge  of  powder  is  ignited. 
The  piston  or  movable  element  of  the  gas-engine  is  driven, 

37 


38 


Aviation  Engines 


from  the  closed  or  head  end  to  the  crank  end  of  the 
cylinder  by  a  similar  expansion  of  gases  resulting  from 
combustion.  The  first  operation  in  firing  a  gun  or  secur- 
ing an  explosion  in  the  cylinder  of  the  gas-engine  is  to 


7.  Cylinder  Filling  with  Gas, 


2,  Piston  Compressing  Gas. 


Inlet  Pipe 

Inlet  Value 
shown  Ope, 

Exhaust  Valv 
Closed 

Exhaust  Pipe 
Vo/t/.e  Spring 


Cam 


Camshaft 


Cylinder  Filled  with 
'  Combustible  Gas 


Cooling  Flanges 


Piston  Ascending 


Lower  Half 
Cranhcase 


'amrod 


/.  Powder  Inserted. 


2.  Powder  Compressed. 


Fig.  5. — Outlining  First  Two  Strokes  of  Piston  in  Four-Cycle  Engine. 

fill  the  combustion  space  with  combustible  material.  This 
is  done  by  a  down  stroke  of  the  piston  during  which  time 
the  inlet  valve  opens  to  admit  the  gaseous  charge  to  the 
cylinder  interior.  This  operation  is  shown  at  Fig.  5,  A. 
The  second  operation  is  to  compress  this  gas  which  is 
done  by  an  upward  stroke  of  the  piston  as  shown  at  Fig, 


Internal  Combustion  Engine  Action 


39 


5,  B.  When  the  top  of  the  compression  stroke  is  reached, 
the  gas  is  ignited  and  the  piston  is  driven  down  toward 
the  open  end  of  the  cylinder,  as  indicated  at  Fig.  6,  C«  The 
fourth  operation  or  exhaust  stroke  is  performed  by  the 


8.  Compressed  Gas  Exploded. 


4.  Inert  Gases  Exhausted, 


Bath  Values  Closed 


Spark  Plug 
Cooling  Flanges 


serf  Oas 
~       Being  Ignited 
3         by  Spark. 


3.  Powder  Exploded. 


4.  Powder  Gas  Exhausted. 


Fig.  6. — Outlining  Second  Two  Strokes  of  Piston  in  Four-Cycle  Engine. 

return  upward  movement  of  the  piston  as  shown  at  Fig. 
6,  D  during  which  time  the  exhaust  valve  is  opened  to 
permit  the  burnt  gases  to  leave  the  cylinder.  As  soon 
as  the  piston  reaches  the  top  of  its  exhaust  stroke,  the 
energy  stored  in  the  fly-wheel  rim  during  the  power  stroke 
causes  that  member  to  continue  revolving  and  as  the  piston 


40 


Aviation  Engines 


Spark  Plug ._ 

Gas  Flowing  ;n-.s 


Piston  Goes 
Down 


Connecting 
Rod 


.A-  Intake  Stroke 
Water  Space  — 


Gas  ai 
High  Press  u  re  •- 


Piston 

Goes  Down-. — "' 


Cylinder  - — 


C-  Power  Stroke 


D- Exhaust  Stroke 


Fig.    7. — Sectional   View  of   L   Head   Gasoline    Engine    Cylinder   Showing 
Piston  Movements  During  Four-Stroke  Cycle. 


How  Two-Stroke  Cycle  Engine  Works  41 

again  travels  on  its  down  stroke  the  inlet  valve  opens  and 
admits  a  charge  of  fresh  gas  and  the  cycle  of  operations 
is  repeated. 

The  illustrations  at  Fig.  7  show  how  the  various  cycle 
functions  take  place  in  an  L  head  type  water  cooled  cyl- 
inder engine.  The  sections  at  A  and  C  are  taken  through 
the  inlet  valve,  those  at  B  and  D  are  taken  through  the 
exhaust  valve. 

The  two-cycle  engine  works  on  a  different  principle,  as 
while  only  the  combustion  chamber  end  of  the  piston  is 
employed  to  do  useful  work  in  the  four-cycle  engine,  both 
upper  and  lower  portions  are  called  upon  to  perform  the 
functions  necessary  to  two-cycle  engine  operation.  In- 
stead of  the  gas  being  admitted  into  the  cylinder  as  is  the 
case  with  the  four-stroke  engine,  it  is  first  drawn  into  the 
engine  base  where  it  receives  a  preliminary  compression 
prior  to  its  transfer  to  the  working  end  of  the  cylinder. 
The  views  at  Fig.  8  should  indicate  clearly  the  operation 
of  the  two-port  two-cycle  engine.  At  A  the  piston  is 
seen  reaching  the  top  of  its  stroke  and  the  gas  above  the 
piston  is  being  compressed  ready  for  ignition,  while  the 
suction  in  the  engine  base  causes  the  automatic  valve  to 
open  and  admits  mixture  from  the  carburetor  to  the 
crank  case.  When  the  piston  reaches  the  top  of  its  stroke, 
the  compressed  gas  is  ignited  and  the  piston  is  driven 
down  on  the  power  stroke,  compressing  the  gas  in  the 
engine  base. 

When  the  top  of  the  piston  uncovers  the  exhaust  port 
the  flaming  gas  escapes  because  of  its  pressure.  A  down- 
ward movement  of  the  piston  uncovers  the  inlet  port 
opposite  the  exhaust  and  permits  the  fresh  gas  to  bypass 
through  the  transfer  passage  from  the  engine  base  to  the 
cylinder.  The  conditions  with  the  intake  and  exhaust 
port  fully  opened  are  clearly  shown  at  Fig.  8,  C.  The 
deflector  plate  on  the  top  of  the  piston  directs  the  enter- 
ing fresh  gas  to  the  top  of  the  cylinder  and  prevents  the 
main  portion  of  the  gas  stream  from  flowing  out  through 
the  open  exhaust  port.  On  the  next  upstroke  of  the  piston 


42 

r 


Aviation  Engines 


§ 

£ 


bO 

I 


How  Two-Stroke  Cycle  Engine  Works 


I 

H 

fao 


44  Aviation  Engines 

the  gas  in  the  cylinder  is  compressed  and  the  inlet  valve 
opened,  as  shown  at  A  to  permit  a  fresh  charge  to  enter 
the  engine  base. 

The  operating  principle  of  the  three-port,  two-cycle 
engine  is  practically  the  same  as  that  previously  described 
with  the  exception  that  the  gas  is  admitted  to  the  crank- 
case  through  a  third  port  in  the  cylinder  wall,  which  is 
uncovered  by  the  piston  when  that  member  reaches  the 
end  of  its  upstroke.  The  action  of  the  three-port  form 
can  be  readily  ascertained  by  studying  the  diagrams  given 
at  Fig.  9.  Combination  two-  and  three-port  engines  have 
been  evolved  and  other  modifications  made  to  improve  the 
action. 

THE    TWO-CYCLE    AND    FOUK-CYCLE    TYPES 

In  the  earlier  years  of  explosive-motor  progress  was 
evolved  the  two  types  of  motors  in  regard  to  the  cycles 
of  their  operation.  The  early  attempts  to  perfect  the 
two-cycle  principle  were  for  many  years  held  in  abeyance 
from  the  pressure  of  interests  in  the  four-cycle  type,  until 
its  simplicity  and  power  possibilities  were  demonstrated 
by  Mr.  Dugald  Clerk  in  England,  who  gave  the  principles 
of  the  two-cycle  motor  a  broad  bearing  leading  to  im- 
mediate improvements  in  design,  which  has  made  further 
progress  in  the  United  States,  until  at  the  present  time 
it  has  an  equal  standard  value  as  a  motor-power  in  some 
applications  as  its  ancient  rival  the  four-cycle  or  Otto 
type,  as  demonstrated  by  Beau  de  Eocha  in  1862. 

Thermodynamically,  the  methods  of  the  two  types  are 
equal  as  far  as  combustion  is  concerned,  and  compression 
may  favor  in  a  small  degree  the  four-cycle  type  as  well 
as  the  purity  of  the  charge.  The  cylinder  volume  of  the 
two-cycle  motor  is  much  smaller  per  unit  of  power,  and 
the  enveloping  cylinder  surface  is  therefore  greater  per 
unit  of  volume.  Hence  more  heat  is  carried  off  by  the 
jacket  water  during  compression,  and  the  higher  com- 
pression available  from  this  tends  to  increase  the  economy 
during  compression  which  is  lost  during  expansion. 


Two-  and  Four-Stroke  Cycles  Compared          45 

From  the  above  considerations  it  may  be  safely  stated 
that  a  lower  temperature  and  higher  pressure  of  charge 
at  the  beginning  of  compression  is  obtained  in  the  two- 
cycle  motor,  greater  weight  of  charge  and  greater  specific 
power  of  higher  compression  resulting  in  higher  thermal 
efficiency.  The  smaller  cylinder  for  the  same  power  of 
the  two-cycle  motor  gives  less  friction  surface  per  impulse 
than  of  the  other  type;  although  the  crank-chamber  pres- 
sure may,  in  a  measure,  balance  the  friction  of  the  four- 
cycle type.  Probably  the  strongest  points  in  favor  of  the 
two-cycle  type  are  the  lighter  fly-wheel  and  the  absence 
of  valves  and  valve  gear,  making  this  type  the  most  simple 
in  construction  and  the  lightest  in  weight  for  its  developed 
power.  Yet,  for  the  larger  power  units,  the  four-cycle 
type  will  no  doubt  always  maintain  the  standard  for 
efficiency  and  durability  of  action. 

The  distribution  of  the  charge  and  its  degree  of  mix- 
ture with  the  remains  of  the  previous  explosion  in  the 
clearance  space,  has  been  a  matter  of  discussion  for  both 
types  of  explosive  motors,  with  doubtful  results.  In  Fig. 
10,  A  we  illustrate  what  theory  suggests  as  to  the  distribu- 
tion of  the  fresh  charge  in  a  two-cycle  motor,  and  in  Fig. 
10,  B  what  is  the  probable  distribution  of  the  mixture  when 
the  piston  starts  on  its  compressive  stroke.  The  arrows 
show  the  probable  direction  of  flow  of  the  fresh  charge 
and  burnt  gases  at  the  crucial  moment. 

In  Fig.  10,  C  is  shown  the  complete  out-sweep  of  the 
products  of  combustion  for  the  full  extent  of  the  piston 
stroke  of  a  four-cycle  motor,  leaving  only  the  volume  of 
the  clearance  to  mix  with  the  new  charge  and  at  D  the 
manner  by  which  the  new  charge  sweeps  by  the  ignition 
device,  keeping  it  cool  and  avoiding  possibilities  of  pre- 
ignition  by  undue  heating  of  the  terminals  of  the  sparking 
device.  Thus;  by  enveloping  the  sparking  device  with 
the  pure  mixture,  ignition  spreads  through  the  charge  with 
its  greatest  possible  velocity,  a  most  desirable  condition 
in  high-speed  motors  with  side-valve  chambers  and  igni- 
ters within  the  valve  chamber. 


46 


Aviation  Engines 


Theoretical  condition. 


Exhaust. 


— H 


Practical  condition. 


D 


New  charge. 


Pig.  10. — Diagrams  Contrasting  Action  of  Two-  and  Four-Cycle  Cylinders 
on  Exhaust  and  Intake  Stroke. 


Internal  Combustion  Engine  Theory  47 


THEORY    OF   THE    GAS    AND   GASOLINE    ENGINE 

The  laws  controlling  the  elements  that  create  a  power 
by  their  expansion  by  heat  due  to  combustion,  when  prop- 
erly understood,  become  a  matter  of  -  computation  in 
regard  to  their  value  as  an  agent  for  generating  power 
in  the  various  kinds  of  explosive  engines.  The  method 
of  heating  the  elements  of  power  in  explosive  engines 
greatly  widens  the  limits  of  temperature  as  available  in 
other  types  of  heat-engines.  It  disposes  of  many  of  the 
practical  troubles  of  hot-air,  and  even  of  steam-engines, 
in  the  simplicity  and  directness  of  application  of  the  ele- 
ments of  power.  In  the  explosive  engine  the  difficulty 
of  conveying  heat  for  producing  expansive  effect  by  con- 
vection is  displaced  by  the  generation  of  the  required  heat 
within  the  expansive  element  and  at  the  instant  of  its 
useful  work.  The.  low  conductivity  of  heat  to  and  from 
air  has  been  the  great  obstacle  in  the  practical  develop- 
ment of  the  hot-air  engine;  while,  on  the  contrary,  it  has 
become  the  source  of  economy  and  practicability  in  the 
development  of  the  internal-combustion  engine. 

The  action  of  air,  gas,  and  the  vapors  of  gasoline  and 
petroleum  oil,  whether  singly  or  mixed,  is  affected  by 
changes  of  temperature  practically  in  nearly  the  same 
ratio;  but  when  the  elements  that  produce  combustion  are 
interchanged  in  confined  spaces,  there  is  a  marked  differ- 
ence of  effect.  The  oxygen  of  the  air,  the  hydrogen  and 
carbon  of  a  gas,  or  vapor  of  gasoline  or  petroleum  oil  are 
the  elements  that  by  combustion  produce  heat  to  expand 
the  nitrogen  of  the  air  and  the  watery  vapor  produced 
by  the  union  of  the  oxygen  in  the  iair  and  the  hydrogen  in 
the  gas,  as  well  as  also  the  monoxide  and  carbonic-acid 
gas  that  may  be  formed  by  the  union  of  the  carbon  of 
gas  or  vapor  with  part  of  the  oxygen  of  the  air.  The 
various  mixtures  as  between  air  and  gas,  or  air  and  vapor, 
with  the  proportion  of  the  products  of  combustion  left 
in  the  cylinder  from  a  previous  combustion,  form  the 
elements  to  be  considered  in  estimating  the  amount  of 


48  Aviation  Engines 

pressure  that  may  be.  obtained  by  their  combustion  and 
expansive  force. 

EARLY  GAS   ENGINE   FOKMS 

The  working'  process  of  the  explosive  motor  may  be 
divided  into  three  principal  types :  1.  Motors  with  charges 
igniting  at  constant  volume  without  compression,  such  as 
the  Lenoir,  Hugon,  and  other  similar  types  now  abandoned 
as  wasteful  in  fuel  and  effect.  2.  Motors  with  charges 
igniting  at  constant  pressure  with  compression,  in  which 
a  receiver  is  charged  by  a  pump  and  the  gases  burned 
while  being  admitted  to  the  motor  cylinder,  such  as  types 
of  the  Simon  and  Brayton  engine.  3.  Motors  with  charges 
igniting  at  constant  volume  with  variable  compression, 
such  as  the  later  two-  and  four-cycle  motors  with  compres- 
sion of  the  indrawn  charge;  limited  in  the  two-cycle  type 
and  variable  in  the  four-cycle  type  with  the  ratios  of  the 
clearance  space  in  the  cylinder.  This  principle  produces 
the  explosive  motor  of  greatest  efficiency. 

The  phenomena  of  the  brilliant  light  and  its  accom- 
panying heat  at  the  moment  of  explosion  .have  been  wit- 
nessed in.  the  experiments  of  Dugald  Clerk  in  England, 
the  illumination  lasting  throughout  the  stroke;  but  in 
regard  to  time  in  a  four-cycle  engine,  the  incandescent 
state  exists  only  one-quarter  of  the  running  time.  Thus 
the  time  interval,  together  with  the  non-conductibility  of 
the  gases,  makes  the  phenomena  o*f  a  high-temperature 
combustion  within  the  comparatively  cool  walls  of  a  cyl- 
inder a  practical  possibility. 

THE  ISOTHERMAL  LAW 

The  natural  laws,  long  since  promulgated  by  Boyle, 
Gay  Lussac,  and  others,  on  the  subject  of  the  expansion 
and  compression  of  gases  by  force  and  by  heat,  and  their 
variable  pressures  and  temperatures  when  confined,  are 
conceded  to  be  practically  true  and  applicable  to  all  gases, 
whether  single,  mixed,  or  combined. 


Isothermal  Law.  49 

The  law  formulated  by  Boyle  only  relates  to  the  com- 
pression and  expansion  of  gases  without  a  change  •  of 
temperature,  and  is  stated  in  these  words: 

//  the  temperature  of  a  gas  be  kept  constant,  its  pres- 
sure or  elastic  force  will  vary  inversely  as  the  volume 
it  occupies. 

It  is  expressed  in  the  formula  P  X  V  -  =  C,  or  pressure 

C  C 

X  volume  =  constant.    Hence,  —  =  V  and  —  =  P. 

P  V 

Thus  the  curve  formed  by  increments  of  pressure  dur- 
ing the  expansion  or  compression  of  a  given  volume  of 
gas  without  change  of  temperature  is  designated  as  the 
isothermal  curve  in  which  the  volume  multiplied  by  the 
pressure  is.  a  constant  value  in  expansion,  and  inversely 
the  pressure  divided  by  the  volume  is  a  constant  value 
in  compressing  a  gas. 

But  as  compression  and  expansion  of  gases  require 
force  for  their  accomplishment  mechanically,  or  by  the 
application  or  abstraction  of  heat  chemically,  or  by  con- 
vection, a  second  condition  becomes  involved,  which  was 
formulated  into  a  law  of  thermodynamics  by  Gay  Lussac 
under  the  following  conditions:  A  given  volume  of  gas 
under  a  free  piston  expands  by  heat  and  contracts  by  the 
loss  of  heat,  its  volume  causing  a  proportional  movement 
of  a  free  piston  equal  to  ^73  part  of  the  cylinder  volume 
for  each  degree  Centigrade  difference  in  temperature,  or 
%92  part  of  its  volume  for  each  degree  Fahrenheit.  "With 
a  fixed  piston  (constant  volume),  the  pressure  is  increased 
or  decreased  by  an  increase  or  decrease  of  heat  in  the 
same  proportion  of  %TS  part  of  its  pressure  for  each 
degree  Centigrade,  or  %92  part  of  its  pressure  for  each 
degree  Fahrenheit  change  in  temperature.  This  is  the 
natural  sequence  of  the  law  of  mechanical  equivalent, 
which  is  a  necessary  deduction  from  the  principle  that 


50  Aviation  Engines 

nothing  in  nature  can  be  lost  or  wasted,  for  all  the  heat 
that  is  imparted  to  or  abstracted  from  a  gaseous  body 
must  be  accounted  for,  either  as  heat  or  its  equivalent 
transformed  into  some  other  form  of  energy.  In  the  case 
of  a  piston  moving  in  a  cylinder  by  the  expansive  force 
of  heat  in  a  gaseous  body,  all  the  heat  expended  in  ex- 
pansion of  the  gas  is  turned  into  work;  the  balance  must 
be  accounted  for  in  absorption  by  the  cylinder  or  radiation. 

THE  ADIABATIC  LAW 

This  theory  is  equally  applicable  to  the  cooling  of  gases 
by  abstraction  of  heat  or  by  cooling  due  to  expansion  by 
the  motion  of  a  piston.  The  denominators  of  these  heat 
fractions  of  expansion  or  contraction  represent  the  ab- 
solute zero  of  cold  below  the  freezing-point  of  water,  and 
read  — 273°  C.  or  —  492.66°  =  —460.66°  F.  below  zero: 
and  these  are  the  starting-points  of  reference  in  com- 
puting the.  heat  expansion  in  gas-engines.  According  to 
Boyle's  law,  called  the  first  law  of  gases,  there  are  but 
two  characteristics  of  a  gas  and  their  variations  to  be 
considered,  viz.,  volume  and  pressure:  while  by  the  law 
of  Gay  Lussac,  called  the  second  law  of  gases,  a  third 
is  added,  consisting  of  the  value  of  the  absolute  tem- 
perature, counting  from  absolute  zero  to  the  temperatures 
at  which  the  operations  take  place.  This  is  the  Adiabatic 
law. 

The  ratio  of  the  variation  of  the  three  conditions  — 
volume,  pressure,  and  heat  —  from  the  absolute  zero  tem- 
perature has  a  certain  rate,  in  which  the  volume  multi- 
plied by  the  pressure  and  the  product  divided  by  the 
absolute  temperature  equals  the  ratio  of  expansion  for 
each  degree.  '  If  a  volume  of  air  is  contained  in  a  cylinder 
having  a  piston  and  fitted  with  an  indicator,  the  piston, 
if  moved  to  and  fro  slowly,  will  alternately  compress  and 
expand  the  air,  and  the  indicator  pencil  will  trace  a  line 
or  lines  upon  the  card,  which  lines  register  the  change 
of  pressure  and  volume  occurring  in  the  cylinder.  If  the 
piston  is  perfectly  free  from  leakage,  and  it  be  supposed 


Adiabatic  Law 


51 


that  the  temperature  of  the  air  is  kept  quite  constant, 
then  the  line  so  traced  is  called  an  Isothermal  line,  and 
the  pressure  at  any  point  when  multiplied  by  the  volume 
is  a  constant,  according  to  Boyle's  law, 

pv  =  a  constant. 

If,  however,  the  piston  is  moved  very  rapidly,  the  air  will 
not  remain  at  constant  temperature,  but  the  temperature 
will  increase  because  work  has  been  done  upon  the  air, 


w 

13 

20 

c 

\ 

W  30 

\ 

\ 

10 

\ 

' 

\2 

17J 

C 

80 

\ 

\ 

V 

V« 

70 

s 

\\ 

S 

V-"- 

\ 

</ 

\ 

\ 

15 

0.5 

C 

\ 

V" 

X 

40 
30 

x^ 

^ 

\ 

v^ 

20 

^~~-  — 

-—. 

== 

=^_ 

^: 

=: 

=== 

=s 

•^ 

—  _ 

10 

ATMOSPHERIC 

LINES 


0    10   20    30   40   50    60   70   80    90  100 

VOLUME 

Fig.  11. — Diagram  Isothermal  and  Adiabatic  Lines. 


and  the  heat  has  no  time  to  escape  by  conduction.  If  no 
heat  whatever  is  lost  by  any  cause,  the  line  will  be  traced 
over  and  over  again  by  the  indicator  pencil,  the  cooling 
by  expansion  doing  work  precisely  equalling  the  heating 
by  compression.  This  is  the  line  of  no  transmission  of 
heat,  therefore  known  as  Adiabatic. 

The  expansion  of  a  gas  %73  of  its  volume  for  every 
degree  Centigrade,  added  to  its  temperature,  is  equal  to 
the  decimal  .00366,  the  coefficient  of  expansion  for  Centi- 
grade units.  To  any  given  volume  of  a  gas,  its  expansion 
may  be  computed  by  multiplying  the  coefficient  by  the 


52  Aviation  Engines 

number  of  degrees,  and  by  reversing  the  process  the  degree 
of  acquired  heat  may  be  obtained  approximately.  These 
methods  are  not  strictly  in  conformity  with  the  absolute 
mathematical  formula,  because  there  is  a  small  increase 
in  the  increment  of  expansion  of  a  dry  gas,  and  there  is 
also  a  slight  difference  in  the  increment  of  expansion  due 
to  moisture  in  the  atmosphere  and  to  the  vapor  of  water 
formed  by  the  union  of  the  hydrogen  and  oxygen  in  the 
combustion  chamber  of  explosive  engines. 

TEMPERATURE    COMPUTATIONS 

The  ratio  of  expansion  on  the  Fahrenheit  scale  is  de- 
rived from  the  absolute  temperature  below  the  freezing- 
point  of  water  (32°)  to  correspond  with  the  Centigrade 

1 

scale ;  therefore  -  =  .0020297,  the  ratio  of  expansion 

492.66 

from  32°  for  each  degree  rise  in  temperature  on  the  Fah- 
renheit scale.  As  an  example,  if  the  temperature  of  any 
volume  of  air  or  gas  at  constant  volume  is  raised,  say 
from  60°  to  2000°  F.,  the  increase  in  temperature  will  be 

1 

1940°.    The  ratio  will  be =  .0019206.     Then  by  the 

520.66 

formula : 

Eatio  X  acquired  temp.  X  initial  pressure  =  the  gauge 
pressure;  and  .0019206  X  1940°  X  14.7  ==  54.77  Ibs. 

By  another  formula,  a  convenient  ratio  is  obtained  by 

absolute  pressure        14.7 

or =  .023233;  then,  using  the  dif- 

absolute  temp.         520.66 

ference  of  temperature  as  before,  .028233  X  1940°  ==  54.77 
Ibs.  pressure. 

By  another  formula,  leaving  out  a  small  increment  due 
to  specific  heat  at  high  temperatures: 


Temperature  Computations  53 

Atmospheric  pressure  X  absolute  temp. 
+  acquired  temp. 

_L. — 

Absolute  temp.  +  initial  temp. 

absolute  pressure  due  to  the  acquired  temperature,  from 
which  the  atmospheric  pressure  is  deducted  for  the 
gauge  pressure.  Using,  the  foregoing  example,  we  have 

14.7  X  460.66°  +  2000° 

-  =  69.47  —  14.7  =  54.77,   the   gauge 
460.66  +  60° 

pressure,  460.66  being  the  absolute  temperature  for  zero 
Fahrenheit. 

For  obtaining  the  volume  pf  expansion  of  a  gas  from 
a  given  increment  of  heat,  we  have  the  approximate 
formula : 

Volume  X  absolute  temp.  +  acquired  temp. 

II.  -  -  —  heated 

Absolute  temp.  +  initial  temp. 

volume.  In  applying  this  formula  to  the  foregoing  ex- 
ample, the  figures  become: 

460.66°  +  2000° 

I.  x  —  -  =  4.72604  volumes. 

460.66  +  60° 

From  this  last  term  the  gauge  pressure  may  be  obtained 
as  follows: 

III.  4.72604  X  14.7  =  69.47  Ibs.  absolute  — 14.7  Ibs.  at- 
mospheric pressure  —  54.77  Ibs.  gauge  pressure ;  which  is 
the  theoretical  pressure  due  to  heating  air  in  a  confined 
space,  or  at  constant  volume  from  60°  to  2000°  F. 

By  inversion  of  the  heat  formula  for  absolute  pressure 
we  have  the  formula  for  the  acquired  heat,  derived  from 
combustion  at  constant  volume  from  atmospheric  pressure 
to  gauge  pressure  plus  atmospheric  pressure  as  derived 
from  Example  L,  by  which  the  expression 

absolute  pressure  X  absolute  temp.  +  initial  temp, 
initial  absolute  pressure 


54  Aviation  Engines 

=  absolute  temperature  +  temperature  of  combustion, 
from  which  the  acquired  temperature  is  obtained  by  sub- 
tracting the  absolute  temperature. 

69.47  X  460.66  +  60 

Then,  for  example,  —        =  2460.66,  and 

14.7 

2460.66  —  460.66  =  2000°,  the  theoretical  heat  of  combus- 
tion. The  dropping  of  terminal  decimals  makes  a  small 
decimal  difference  in  the  result  in  the  different  formulas. 

\ 

HEAT   AND   ITS   WORK 

By  Joule's  law  of  the  mechanical  equivalent  of  heat, 
whenever  heat  is  imparted  to  an  elastic  body,  as  air  or 
gas,  energy  is  generated  and  mechanical  work  produced 
by  the  expansion  of  the  air  or  gas.  When  the  heat  is  im- 
parted by  combustion  within  a  cylinder  containing  a  mov- 
able piston,  the  mechanical  work  becomes  an  amount 
measurable  by  the  observed  pressure  and  movement  of 
the  piston.  The  heat  generated  by  the  explosive  elements 
and  the  expansion  of  the  non-combining  elements  of  nitro- 
gen and  water  vapor  that  may  have  been  injected  into  the 
cylinder  as  moisture  in  the  air,  and  the  water  vapor 
formed  by  the  union  of  the  oxygen  of  the  air  with  the 
hydrogen  of  the  gas,  all  add  to  the  energy  of  the  work 
from  their  expansion  by  the  heat  of  internal  combustion. 
As  against  this,  the  absorption  of  heat  by  the  walls  of  the 
cylinder,  the  piston,  and  cylinder-head  or  clearance  walls, 
becomes  a  modifying  condition  in  the  force  imparted  to 
the  moving  piston. 

It  is  found  that  when  any  explosive  mixture  of  air  and 
gas  or  hydrocarbon  vapor  is  fired,  the  pressure  falls  far 
short  of  the  pressure  computed  from  the  theoretical  effect 
of  the  heat  produced,  and  from  gauging  the  expansion  of 
the  contents  of  a  cylinder.  It  is  now  well  known  that  in 
practice  the  high  efficiency  which  is  promised  by  theoret- 
ical calculation  is  never  realized;  but  it  must  always  be 


Heat  and  Its  Work  55 

remembered  that  the  heat  of  combustion  is  the  real  agent, 
and  that  the  gases  and  vapors  are  but  the  medium  for  the 
conversion  of  inert  elements  of  power  into  the  activity  of 
energy  by  their  chemical  union.  The  theory  of  combustion 
has  been  the  leading  stimulus  to  large  expectations  with 
inventors  and  constructors  of  explosive  motors;  its  en- 
tanglement with  the  modifying  elements  in  practice  has 
delayed  the  best  development  in  construction,  and  as  yet 
no  really  positive  design  of  best  form  or  action  seems  to 
have  been  accomplished,  although  great  progress  has  been 
made  during  the  past  decade  in  the  development  of  speed, 
reliability,  economy,  and  power  output  of  the  individual 
units  of  this  comparatively  new  power. 

One  of  the  most  serious  difficulties  in  the  practical  de- 
velopment of  pressure,  due  to  the  theoretical  computations 
of  the  pressure  value  of  the  full  heat,  is  probably  caused 
by  imparting  the  heat  of  the  fresh  charge  to  the  balance 
of  the  previous  charge  that  has  been  cooled  by  expansion 
from  the  maximum  pressure  to  near  the  atmospheric 
pressure  of  the  exhaust.  The  retardation  in  the  velocity 
of  combustion  of  perfectly  mixed  elements  is  now  well 
known  from  experimental  trials  with  measured  quantities; 
but  the  principal  difficulty  in  applying  these  conditions 
to  the  practical  work  of  an  explosive  engine  where  a  ne- 
cessity for  a  large  clearance  space  cannot  be  obviated, 
is  in  the  inability  to  obtain  a  maximum  effect  from  the 
imperfect  mixture  and  the  mingling  of  the  products  of 
the  last  explosion  with  the  new  mixture,  which  produces 
a  clouded  condition  that  makes  the  ignition  of  the  mass 
irregular  or  chattering,  as  observed  in  the  expansion  lines 
of  indicator  cards;  but  this  must  not  be  confounded  with 
the  reaction  of  the  spring  in  the  indicator. 

Stratification  of  the  mixture  has  been  claimed  as  taking 
place  in  the  clearance  chamber  of  the  cylinder;  but  this 
is  not  a  satisfactory  explanation  in  view  of  the  vortical 
effect  of  the  violent  injection  of  the  air  and  gas  or  vapor 
mixture.  It  certainly  cannot  become  a  perfect  mixture 
in  the  time  of  a  stroke  of  a  high-speed  motor  of  the  two- 


56 


Aviation  Engines 


cycle  class.  In  a  four-cycle  engine,  making  1,500  revolu- 
tions per  minute,  the  injection  and  compression  in  any 
one  cylinder  take  place  in  one  twenty-fifth  of  a  second- 
formerly  considered  far  too  short  a  time  for  a  perfect 
infusion  of  the  elements  of  combustion  but  noAV  very  easily 
taken  care  of  despite  the  extremely  high  speed  of  numer- 
ous aviation  and  automobile  power-plants. 

TABLE   I. — EXPLOSION   AT   CONSTANT  VOLUME   IN   A   CLOSED   CHAMBER. 


Dia- 
gram 
Curve 
Fig.  8. 

Mixture  Injected. 

Temp,  of 
Injection 
Fahr. 

Time 
of  Explo- 
sion. 
Second. 

Observed 
Gauge 
Pressure. 
Pounds. 

Com- 
puted 
Temp. 
Fahr. 

a 

1  volume  gas  to  14  volumes  air. 

64° 

0.45 

40. 

1,483° 

b 

1 

13 

51° 

0.31 

51.5 

1,859° 

c 

1 

12 

51° 

0.24 

60. 

2,195° 

d 

1 

11 

51° 

0.17 

61. 

2,228° 

e 

1 

9 

62° 

0.08 

78. 

2,835° 

f 

1 

7 

62° 

0.06 

87. 

3,151° 

9 

1 

6 

51° 

0.04 

90. 

3,257° 

h 

1 

5 

51° 

0.055 

91. 

3,293° 

i 

1 

4 

66° 

0.16            80. 

2,871° 

In  an  examination  of  the  times  of  explosion  and  the 
corresponding  pressures  in  both  tables,  it  will  be  seen  that 
a  mixture  of  1  part  gas  to  6  parts  air  is  the  most  effective 
and  will  give  the  highest  mean  pressure  in  a  gas-engine. 
There  is  a  limit  to  the  relative  proportions  of  illuminating 
gas  and  air  mixture  that  is  explosive,  somewhat  variable, 
depending  upon  the  proportion  of  hydrogen  in  the  gas. 
With  ordinary  coal-gas,  1  of  gas  to  15  parts  of  air;  and 
on  the  lower  end  of  the  scale,  1  volume  of  gas  to  2  parts 
air,  are  non-explosive.  With  gasoline  vapor  the  explosive 
effect  ceases  at  1  to  16,  and  a  saturated  mixture  of  equal 
volumes  of  vapor  and  air  will  not  explode,  while  the  most 
intense  explosive  effect  is  from  a  mixture  of  1  part  vapor 
to  9  parts  air.  In  the  use  of  gasoline  and  air  mixtures 
from  a  carburetor,  the  best  effect  is  from  1  part  saturated 
air  to  8  parts  free  air. 


Heat  and  Its  Work 


57 


TABLE  II. — PROPERTIES  AND  EXPLOSIVE  TEMPERATURE  OF  A  MIXTURE  OF 
ONE  PART  OF  ILLUMINATING  GAS  OF  660  THERMAL  UNITS  PER  CUBIC  FOOT 
WITH  VARIOUS  PROPORTIONS  OF  AIR  WITHOUT  MIXTURE  OF  CHARGE  WITH 
THE  PRODUCTS  OF  A  PREVIOUS  EXPLOSION. 


i 

o 

j= 

g 

JJi 

11 

3  . 

3  g 

il 

Specific  Heat. 
Heat  Units  Required 
to  Raise  1  Lb.  1  Deg. 
Fahrenheit. 

Heat  to 
Raise  One 
Cubic 
Foot  of 

Id 

^! 

Ratio 
Col. 

3  w" 

!| 

G** 

C«-i 

Mixture 

§ 

U$£ 

03    S  IQ 

2  **> 
23.fi 

—  0 
TO  jj 

c§ 

1  Deg. 
Fahr. 

'3  § 
PC 

1 

*g£ 

§* 

§£ 

Constant 

Constant 

1 

^  2  1« 

£ 

Pressure. 

Volume. 

& 

P 

6  to  i 

.074195 

.2668 

.1913 

.014189 

94.28 

6644.6 

.465 

3090 

.  7  to  1 

.075012 

.2628 

.1882 

.014116 

82. 

5844.4 

.518 

3027 

8  to  1    . 

.075647 

.2598 

.1858 

.014059 

73.33 

5216.1 

.543 

2832 

9  to  1    . 

.076155 

.2575 

.1846 

.014013 

66. 

4709.9 

.56 

2637 

10  to  1    . 

.076571 

.2555 

.1825 

.013976 

60. 

4293. 

.575 

2468 

11  to  1    . 

.076917 

.2540 

.1813 

.013945 

55. 

3944. 

.585 

2307 

12  to  1    . 

.077211 

.2526 

.1803 

.013922 

50.77 

3646.7 

.58 

2115 

The  weight  of  a  cubic  foot  of  gas  and  air  mixture  as 
given  in  Col.  2  is  found  by  adding  the  number  of  volumes 
of  air  multiplied  by  its  weight,  .0807,  to  one  volume  of  gas 
of  weight  .035  pound  per  cubic  foot  and  dividing  by  the 
total  number  of  volumes;  for  example,  as  in  the  table, 

.5192 
6  X  .0807  = =  .074195  as  in  the  first  line,  and  so  on 

7 

for  any  mixture  or  for  other  gases  of  different  specific 
weight  per  cubic  foot.  The  heat  units  evolved  by  com- 
bustion of  the  mixture  (Col.  6)  are  obtained  by  dividing 
the  total  heat  units  in  a  cubic  foot  of  gas  by  the  total 

660 
proportion  of  the  mixture, =  94.28  as  in  the  first  line 

7 

of  the  table.  Col.  5  is  obtained  by  multiplying  the  weight 
of  a  cubic  foot  of  the  mixture  in  Col.  2  by  the  specific  heat 

Col.  6 

at  a  constant  volume  (Col.  4), =  Col.  7  the  total  heat 

Col.  5 


58  Aviation  Engines 

ratio,  of  which  Col.  8  gives  the  usual  combustion  efficiency 
—  Col.  7  X  Col.  8  gives  the  absolute  rise  in  temperature 
of  a  pure  mixture,  as  given  in  Col.  9. 

The  many  recorded  experiments  made  to  solve  the  dis- 
crepancy between  the  theoretical  and  the  actual  heat  de- 
velopment and  resulting  pressures  in  the  cylinder  of  an 
explosive  motor,  to  which  much  discussion  has  been  given 
as  to  the  possibilities  of  dissociation  and  the  increased 
specific  heat  of  the  elements  of  combustion  and  non-com- 
bustion, as  well,  also,  of  absorption  and  radiation  of  heat, 
have  as  yet  furnished  no  satisfactory  conclusion  as  to 
what  really  takes  place  within  the  cylinder  walls.  There 
seems  to  be  very  little  known  about  dissociation,  and 
somewhat  vague  theories  have  been  advanced  to  explain 
the  phenomenon.  The  fact  is,  nevertheless,  apparent  as 
shown  in  the  production  of  water  and  other  producer 
gases  by  the  use  of  steam  in  contact  with  highly  incan- 
descent fuel.  It  is  known  that  a  maximum  explosive 
mixture  of  pure  gases,  as  hydrogen  and  oxygen  or  car- 
bonic oxide  and  oxygen,  suffers  a  contraction  of  one-third 
their  volume  by  combustion  to  their  compounds,  steam  or 
carbonic  acid.  In  the  explosive  mixtures  in  the  cylinder 
of  a  motor,  however,  the  combining  elements  form  so 
small  a  proportion  of  the  contents  of  the  cylinder  that 
the  shrinkage  of  their  volume  amounts  to  no  more  than 
3  per  cent,  of  the  cylinder  volume.  This  by  no  means 
accounts  for  the  great  heat  and  pressure  differences  be- 
tween the  theoretical  and  actual  effects. 

CONVERSION    OF    HEAT    TO    POWER 

.  The  utilization  of  heat  in  any  heat-engine  has  long 
been  a  theme  of  inquiry  and  experiment  with  scientists 
and  engineers,  for  the  purpose  of  obtaining  the  best  prac- 
tical conditions  and  construction  of  heat-engines  that  would 
represent  the  highest  efficiency  or  the  nearest  approach 
to  the  theoretical  value  of  heat,  as  measured  by  empirical 
laws  that  have  been  derived  from  experimental  researches 
relating  to  its  ultimate  volume.  It  is  well  known  that  the 


Requisites  for  Best  Power  Effect  59 

steam-engine  returns  only  from  12  to  18  per  cent,  of  the 
power  due  to  the  heat  generated  by  the  fuel,  about  25 
per  cent,  of  the  total  heat  being  lost  in  the  chimney,  the 
only  use  of  which  is  to  create  a  draught  for  the  fire;  the 
balance,  some  60  per  cent.,  is  lost  in  the  exhaust  and  by 
radiation.  The  problem  of  utmost  utilization  of  force 
in  steam  has  nearly  reached  its  limit. 

The  internal-combustion  system  of  creating  power  is 
comparatively  new  in  practice,  and  is  but  just  settling 
into  definite  shape  by  repeated  trials  and  modification  of 
details,  so  as  to  give  somewhat  reliable  data  as  to  what 
may  be  expected  from  the  rival  of  the  steam-engine  as 
a  prime  mover.  For  small  powers,  the  gas,  gasoline,  and 
petroleum-oil  engines  are  forging  ahead  at  a  rapid  rate, 
filling  the  thousand  wants  of  manufacture  and  business 
for  a  power  that  does  not  require  expensive  care,  that 
is  perfectly  safe  at  all  times,  that  can  be  used  in  any  place 
in  the  wide  world  to  'which  its  concentrated  fuel  can  be 
conveyed,  and  that  has  eliminated  the  constant  handling 
of  crude  fuel  and  water. 

REQUISITES    FOR   BEST    POWER   EFFECT 

The  utilization  of  heat  in  a  gas-engine  is  mainly  due 
to  the  manner  in  which  the  products  entering  into  com- 
bustion are  distributed  in  relation  to  the  movement  of 
the  piston.  The  investigation  of  the  foremost  exponent 
of  the  theory  of  the  explosive  motor  was  prophetic  in 
consideration  of  "the  later  realization  of  the  best  condi- 
tions under  which  these  motors  can  be  made  to  meet  the 
requirements  of  economy  and  practicability.  As  early  as 
1862,  Beau  de  Kocha  announced,  in  regard  to  the  coming 
power,  that  four  requisites  were  the  basis  of  operation 
for  economy  and  best  effect.  1.  The  greatest  possible 
cylinder  volume  with  the  least  possible  cooling  surface, 
2.  The  greatest  possible  rapidity  of  expansion.  Hence, 
high  speed.  3.  The  greatest  possible  expansion.  Long 
stroke.  4.  The  greatest  possible  pressure  at  the  com- 
mencement of  expansion.  High  compression. 


CHAPTER   III 

Efficiency  of  Internal  Combustion  Engines — Various  Measures  o-f  Effi- 
.      ciency — Temperatures  and  Pressures — Factors  Governing  Economy 
— Losses  in  Wall   Cooling — Value  of  Indicator  Cards — Compres- 
sion in  Explosive  Motors — Factors  Limiting  Compression — Causes 
of  Heat  Losses  and  Inefficiency — Heat  Losses  to  Cooling  Water. 

EFFICIENCY    OF    INTERNAL    COMBUSTION    ENGINES 

EFFICIENCIES  are  worked  out  through  intricate  formulas 
for  a  variety  of  theoretical  and  unknown  conditions  of 
combustion  in  the  cylinder:  ratios  of  clearance  and  cyl- 
inder volume,  and  the  uncertain  condition  of  the  products 
of  combustion  left  from  the  last  impulse  and  the  wall 
temperature.  But  they  are  of  but  little  value,  except  as 
a  mathematical  inquiry  as  to  possibilities.  The  real  com- 
mercial efficiency  of  a  gas  or  gasoline-engine  depends  upon 
the  volume  'of  gas  or  liquid  at  some  assigned  cost,  re- 
quired per  actual  brake  horse-power  per  hour,  in  which 
an  indicator  card  should  show  that  the  mechanical  action 
of  the  valve  gear  and  ignition  was  as  perfect  as  practi- 
cable, and  that  the  ratio  of  clearance,  space,  and  cylinder 
volume  gave  a  satisfactory  terminal  pressure  and  com- 
pression: i.e.,  the  difference  between  the  power  figured 
from  the  indicator  card  and  the  brake  power  being  the 
friction  loss  of  the  engine. 

In  four-cycle  motors  of  the  compression  type,  the  effi- 
ciencies are  greatly  advanced  by  compression,  producing 
a  more  complete  infusion  of  the  mixture  of  gas  or  vapor 
and  air,  quicker  firing,  and  far  greater  pressure  than  is 
possible  with  the  two-cycle  type  previously  described.  In 
the  practical  operation  of  the  gas-engine  during  the  past 
twenty  years,  the  gas-consumption  efficiencies  per  indi- 
cated horse-power  have  gradually  risen  from  17  per  cent, 
to  a  maximum  of  40  per  cent,  of  the  theoretical  heat,  and 

60 


Various  Measures  of  Efficiency  61 

this  has  been  done  chiefly  through  a  decreased  combustion 
chamber  and  increased  compression — the  compression  hav- 
ing gradually  increased  in  practice  from  30  Ibs.  per  square 
inch  to  above  100;  but  there  seems  to  be  a  limit  to  com- 
pression, as  the  efficiency  ratio  decreases  with  greater  in- 
crease in  compression.  It  has  been  shown  that  an  ideal 
efficiency  of  33  per  cent,  for  38  Ibs.  compression  will  in- 
crease to  40  per  cent,  for  66  Ibs.,  and  43  per  cent,  for  88 
Ibs.  compression.  On  the  other  hand,  greater  compression 
means  greater  explosive  pressure  and  greater  strain  on 
the  engine  structure,  which  will  probably  retain  in  future 
practice  the  compression  between  the  limits  of  40  and  90 
Ibs.  except  in  super-compression  engines  intended  for 
high  altitude  work  where  compression  pressures  as  high 
as  125  pounds  have  been  used. 

In  .experiments  made  by  Dugald  Clerk,  in  England, 
with  a  combustion  chamber  equal  to  0.6  of  the  space  swept 
by  the  piston,  with  a  compression  of  38  Ibs.,  the  consump- 
tion of  gas  was  24  cubic  feet  per  indicated  horse-power 
per  hour.  With  0.4  compression  space  and  61  Ibs.  com- 
pression, the  consumption  of  gas  was  20  cubic  feet  per 
indicated  horse-power  per  hour;  and  with  0.34  compres- 
sion space  and  87  Ibs.  compression,  the  consumption  of 
gas  fell  to  14.8  cubic  feet  per  indicated  horse-power  per 
hour — the  actual  efficiencies  being  respectively  17,  21,  and 
25  per  cent.  This  was  with  a  Crossley  four-cycle  engine. 

VARIOUS    MEASURES   OF    EFFICIENCY 

The  efficiencies  in  regard  to  power  in  a  heat-engine 
may  be  divided  into  four  kinds,  as  follows:  I.  The  first 
is  known  as  the  maximum  theoretical  efficiency  of  a  per- 
fect engine  (represented  by  the  lines  in  the  indicator  dia- 

T!  —  T0 

gram).    It  is  expressed  by  the  formula and  shows 

T, 

the  work  of  a  perfect  cycle  in  an  engine  working  between 
the  received  temperature+  absolute  temperature  (TJ  and 


62  Aviation  Engines 

the  initial  atmospheric  temperature •+  absolute  tempera- 
ture (T0).  II.  The  second  is  the  actual  heat  efficiency, 
or  the  ratio  of  the  heat  turned  into  work  to  the  total  heat 
received  by  the  engine.  It  expresses  the  indicated  horse- 
power. III.  The  third  is  the  ratio  between  the  second 
or  actual  heat  efficiency  and  the  first  or  maximum  theo- 
retical efficiency  of  a  perfect  cycle.  It  represents  the 
greatest  possible  utilization  of  the  power  of  heat  in  an 
internal-combustion  engine.  IV.  The  fourth  is  the  me- 


100  Jo 
Supplied 


3  Useful 
Work 


5%  Engjne 
Friction 


Lost  to 
Cooling  Water 


Rejected  in  Exhaust  and  Radiation 


Fig.    12. — Graphic    Diagram    Showing    Approximate    Utilization    of    Fuel 
Burned  in  Internal-Combustion  Engine. 

chanical  efficiency.  This  is  the  ratio  between  the  actual 
horse-power  delivered  by  the  engine  through  a  dyna- 
mometer or  measured  by  a  brake  (brake  horse-power), 
and  the  indicated  horse-power.  The  difference  between 
the  two  is  the  power  lost  by  engine  friction.  In  regard 
to  the  general  heat  efficiency  of  the  materials  of  power 
in  explosive  engines,  we  find  that  with  good  illuminating 
gas  the  practical  efficiency  varies  from  25  to  40  per  cent. ; 
kerosene-motors,  20  to  30;  gasoline-motors,  20  to  32;  acet- 
ylene, 25  to  35;  alcohol,  20  to  30  per  cent,  of  their  heat 
value.  The  great  variation  is  no  doubt  due  to  imperfect 
mixtures  and  variable  conditions  of  the  old  and  new  charge 
in  the  cylinder;  uncertainty  as  to  leakage  and  the  perfec- 


Temperatures  and  Pressures  63 

tion  of  combustion.  In  the  Diesel  motors  operating  under 
high  pressure,  up  to  nearly  500  pounds,  an  efficiency  of 
36  per  cent,  is  claimed. 

The  graphic  diagram  at  Fig.  12  is  of  special  value  as 
it  shows  clearly  how  the  heat  produced  by  charge  combus- 
tion is  expended  in  an  engine  of  average  design. 

On  general  principles  the  greater  difference  between 
the  heat  of  combustion  and  the  heat  at  exhaust  is  the 
relative  measure  of  the  heat  turned  into  work,  which 
represents  the  degree  of  efficiency  without  loss  during 
expansion.  The  mathematical  formulas  appertaining  to 
the  computation  'of  the  element  of  heat  and  its  work  in 
an  explosive  engine  are  in  a  large  measure  dependent 
upon  assumed  values,  as  the  conditions  of  the  heat  of 
combustion  are  made  uncertain  by  the  mixing  of  the  fresh 
charge  with  the  products  of  a  previous  combustion,  and 
by  absorption,  radiation,  and  leakage.  The  computation 
of  the  temperature  from  the  observed  pressure  may  be 
made  as  before  explained,  but  for  compression-engines 
the  needed  starting-points  for  computation  are  very  un- 
certain, and  can  only  be  approximated  from  the  exact 
measure  and  value  of  the  elements  of  combustion  in  a 
cylinder  charge. 

TEMPERATURES    AND    PRESSURES 

Owing  to  the  decrease  from  atmospheric  pressure  in 
the  indrawing  charge  of  the  cylinder,  caused  by  valve  and 
frictional  obstruction,  the  compression  seldom  starts  above 
13  Ibs.  absolute,  especially  in  high-speed  engines.  Col.  3 
in  the  following  table  represents  the  approximate  absolute 
compression  pressure  for  the  clearance  percentage  and 
ratio  in  Cols.  1  and  2,  while  Col.  4  indicates  the  gauge 
pressure  from  the  atmospheric  line.  The  temperatures  in 
Col.  5  are  due  to  the  compression  in  Col.  3  from  an  as- 
sumed temperature  of  560°  F.  in  the  mixture  of  the  fresh 
charge  of  6  air  to  1  gas  with  the  products  of  combustion 
left  in  the  clearance  chamber  from  the  exhaust  stroke  of 
a  medium-speed  motor.  This  temperature  is  subject  to 


64 


Aviation  Engines 


considerable  variation  from  the  difference  in  the  heat- 
unit  power  of  the  gases  and  vapors  used  for  explosive 
power,  as  also  of  the  cylinder-cooling  effect.  In  Col.  6  is 
given  the  approximate  temperatures  of  explosion  for  a 
mixture  of  air  6  to  gas  1  of  660  heat  units  per  cubic  foot, 
for  the  relative  values  of  the  clearance  ratio  in  Col.  2  at 
constant  volume. 

TABLE  III. — GAS-ENGINE  CLEARANCE  RATIOS,  APPROXIMATE  COMPRESSION, 
TEMPERATURES  OF  EXPLOSION  AND  EXPLOSIVE  PRESSURES  WITH  A  MIX- 
TURE OF  GAS  OF  660  HEAT  UNITS  PER  CUBIC  FOOT  AND  MIXTURE  OF  GAS 
1  TO  6  OF  AIR. 


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Lhs. 

Deg. 

Deg. 

.Lbs. 

Lbs. 

Deg. 

.50 

3. 

57. 

42. 

'  822. 

2488 

*169 

144 

2027 

.444 

3.25 

65. 

50. 

846. 

2568 

197 

182 

2107 

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3.50 

70. 

55. 

868. 

2638 

212 

197 

2177 

.363 

3.75 

77. 

62. 

889. 

2701 

234 

219 

2240  . 

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69. 

910. 

2751 

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239 

2290 

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102. 

88. 

955. 

2842 

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288 

2381 

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114. 

99. 

983. 

2901 

336 

321 

2440 

FACTORS   GOVERNING   ECONOMY 

In  view  of  the  experiments  in  this  direction,  it  clearly 
shows  that  in  practical  work,  to  obtain  the  greatest  econ- 
omy per  effective  brake  horse-power,  it  is  necessary:  1st. 
To  transform  the  heat  into  work  with  the  greatest  rapid- 
ity mechanically  allowable.  This  means  high  piston  speed. 
2d.  To  have  high  initial  compression.  3d.  To  reduce  the 
duration  of  contact  between  the  hot  gases  and  the  cylinder 
walls  to  the  smallest  amount  possible;  which  means  short 
stroke  and  quick  speed,  with  a  spherical  cylinder  head. 
4th.  To  adjust  the  temperature  of  the  jacket  water  to 


Losses  in   Wall  Cooling  65 

obtain  the  most  economical  output  of  actual  power.  This 
means  water-tanks  or  water-coils,  with  air-cooling  surfaces 
suitable  and  adjustable  to  the  most  economical  requirement 
of  the  engine,  which  by  late  trials  requires  the  jacket  water 
to  be  discharged  at  about  200°  F.  5th.  To  reduce  the 
wall  surface  of  the  clearance  space  or  combustion  chamber 
to  the  smallest  possible  area,  in  proportion  to  its  required 
volume.  This  lessens  the  loss  of  the  heat  of  combustion  by 
exposure  to  a  large  surface,  and  allows  of  a  higher  mean 
wall  temperature  to  facilitate  the  heat  of  compression. 

LOSSES   IN    WALL   COOLING 

In  an  experimental  investigation  of  the  efficiency  of  a 
gas-engine  under  variable  piston  speeds  made  in  France, 
it  wTas  found  that  the  useful  effect  increases  with  the  ve- 
locity of  the  piston — that  is,  with  the  rate  of  expansion 
of  the  burning  gases  with  mixtures  of  uniform  volumes; 
so  that  the  variations  of  time  of  complete  combustion 
at  constant  pressure,  and  the  variations  due  to  speed,  in 
a  way  compensate  in  their  efficiencies.  The  dilute  mix- 
ture, being  slow  burning,  will  have  its  time  and  pressure 
quickened  by  increasing  the  speed. 

Careful  trials  give  unmistakable  evidence  that  the  use- 
ful effect  increases  with  the  velocity  of  the  piston — that 
is,  with  the  rate  of  expansion  of  the  burning  gases.  The 
time  necessary  for  the  explosion  to  become  complete  and 
to  attain  its  maximum  pressure  depends  not  only  on  the 
composition  of  the  mixture,  but  also  upon  the  rate  of  ex- 
pansion. This  has  been  verified  in  experiments  with  a 
high-speed  motor,  at  speeds  from  500  to  2,000  revolutions 
per  minute,  or  piston  speeds  of  from  16  to  64  feet  per 
second.  The  increased  speed  of  combustion  due  to  in- 
creased piston  speed  is  a  matter  of  great  importance  to 
builders  of  gas-engines,  as  well  as  to  the  users,  as  indi- 
cating the  mechanical  direction  of  improvements  to  lessen 
the  wearing  strain  due  to  high  speed  and  to  lighten  the 
vibrating  parts  with  increased  strength,  in  order  that  the 


66  Aviation  Engines 

balancing  of  high-speed  engines  may  be  accomplished  with 
the  least  weight. 

From  many  experiments  made  in  Europe  and  in  the 
United  States,  it  has  been  conclusively  proved  that  ex- 
cessive cylinder  cooling  by  the  water-jacket  results  in  a 
marked  loss  of  efficiency.  In  a  series  of  experiments  with 
a  simplex  engine  in  France,  it  was  found  that  a  saving 
of  7  per  cent,  in  gas  consumption  per  brake  horse-power 
was  made  by  raising  the  temperature  of  the  jacket  water 
from  141°  to  165°  F.  A  still  greater  saving  was  made  in 
a  trial  with  an  Otto  engine  by  raising  the  temperature  of 
the  jacket  water  from  61°  to  140°  F. — it  being  9.5  per 
cent,  less  gas  per  brake  horse-power. 

It  has  been  stated  that  volumes  of  similar  cylinders 
increase  as  the  cube  of  their  diameters,  while  the  surface 
of  their  cold  walls  varies  as  the  square  of  their  diameters ; 
so  that  for  large  cylinders  the  ratio  of  surface  to  volume 
is  less  than  for  small  ones.  This  points  to  greater  econ- 
omy in  the  larger  engines.  The  study  of  many  experi- 
ments goes  to  prove  that  combustion  takes  place  gradually 
in  the  gas-engine  cylinder,  and  that  the  rate  of  increase 
of  pressure  or  rapidity  of  firing  is  controlled  by  dilution 
and  compression  of  the  mixture,  as  well  as  by  the  rate 
of  expansion  or  piston  speed.  The  rate  of  combustion 
also  depends  on  the  size  and  shape  of  the  explosion  cham- 
ber, and  is  increased  by  the  mechanical  agitation  of  the 
mixture  during  combustion,  and  still  more  by  the  mode 
of  firing. 

VALUE  OF  INDICATOR  CARDS 

To  the  uninitiated,  indicator  cards  are  considerable 
of  a  mystery;  to  those  capable  of  reading  them  they  form 
an  index  relative  to  the  action  of  any  engine.  An  indi- 
cator card,  such  as  shown  at  Fig.  13,  is  merely  a  graphical 
representation  of  the  various  pressures  existing  in  the 
cylinder  for  different  positions  of  the  piston.  The  length 
is  to  some  scale  that  represents  the  stroke  of  the  piston. 
During  the  intake  stroke,  the  pressure  falls  below  the 


Value  of  Indicator  Cards 


67 


atmospheric  line.  During  compression,  the  curve  gradu- 
ally becomes  higher  owing  to  increasing  pressure  as  the 
volume  is  reduced.  After  ignition  the  pressure  line  moves 


F Max1*  Press. 

&  Temp* 


Actual  Indicator 

J)ia(jram  from 

Otto  Engine. 


JZngine] 


Dia. 


•Miri?  Press. 


Atr, 


Admission: 

•T7tis  length  is  proportional  ..totes, strode  of  Engine- 
Tig.  13. — Otta  Four-Cycle  Card. 


upward  almost  straight,  then  as  the  piston  goes  down  on 
the  explosion  stroke,  the  pressure  falls  gradually  to  the 
point  of  exhaust  valve,  opening  when  the  sudden  release 
o't  the  imprisoned  gas  causes  a  reduction  in  pressure  to 
nearly  atmospheric.  An  indicator  card,  or  a  series  of 


V... 


Fig.  14-.— Diesel  Motor  Card. 


them,  will  always  show  by  its  lines  the  normal  or  defective 
condition  of  the  inlet  valve  and  passages;  the  actual  line 
of  compression;  the  firing  moment;  the  pressure  of  ex- 
plosion; the  velocity  of  combustion;  the  normal  or  defec- 
tive line  of  expansion,  as  measured  by  the  adiabatic  curve, 


68  Aviation  Engines 

and  the  normal  or  defective  operation  of  the  exhaust 
valve,  exhaust  passages,  and  exhaust  pipe.  In  fact,  all 
the  cycles  of  an  explosive  motor  may  be  made  a  practical 
study  from  a  close  investigation  of  the  lines  of  an  indi- 
cator card. 

A  most  unique  card  is  that  of  the  Diesel  motor  (Fig. 
14),  which  involves  a  distinct  principle  in  the  design  and 
operation  of  internal-combustion  motors,  in  that  instead 
of  taking  a  mixed  charge  for  instantaneous  explosion,  its 
charge  primarily  is  of  air  and  its  compression  to  a  press- 
ure at  which  a  temperature  is  attained  above  the  igniting 
point  of  the  fuel,  then  injecting  the  fuel  under  a  still 
higher  pressure  by  which  spontaneous  combustion  takes 
place  gradually  with  increasing  volume  over  the  compres- 
sion for  part  of  the  stroke  or  until  the  fuel  charge  is  con- 
sumed. The  motor  thus  operating  between  the  pressures 
of  500  and  35  Ibs.  per  square  inch,  with  a  clearance  of 
about  7  per  cent.,  has  given  an  efficiency  of  36  per  cent, 
of  the  total  heat  value  of  kerosene  oil. 

COMPRESSION  IN  EXPLOSIVE   MOTORS 

That  the  compression  in  a  gas,  gasoline,  or  oil-engine 
has  a  direct  relation  to  the  power  obtained,  has  been  long 
known  to  experienced  builders,  having  been  suggested  by 
M.  Beau  de  Eocha,  in  1862,  and  afterward  brought  into 
practical  use  in  the  four-cycle  or  Otto  type  about  1880. 
The  degree  of  compression  has  had  a  growth  from  zero, 
in  the  early  engines,  to  the  highest  available  due  to  the 
varying  ignition  temperatures  of  the  different  gases  and 
vapors  used  for  explosive  fuel,  in  order  to  avoid  prema- 
ture explosion  from  the  heat  of  compression.  Much  of 
the  increased  power  for  equal-cylinder  capacity  is  due  to 
compression  of  the  charge  from  the  fact  that  the  most 
powerful  explosion  of  gases,  or  of  any  form  of  explosive 
material,  takes  place  when  the  particles  are  in  the  closest 
contact  or  cohesion  with  one  another,  less  energy  in  this 
form  being  consumed  by  the  ingredients  themselves  to 
bring  about  their  chemical  combination,  and  consequently 


Value  of  Compression 


69 


more  energy  is  given  out  in  useful  or  available  work. 
This  is  best  shown  by  the  ignition  of  gunpowder,  which, 
when  ignited  in  the  open  air,  burns  rapidly,  but  without 
explosion,  an  explosion  only  taking  place  if  the  powder 
be  confined  or  compressed  into  a  small  space. 


.20 


.222 


Piston  Stroke  Volume 

.25  .285  .333     .363      .40     .444      .50 


Fig.  15. — Diagram  of  Heat  in  the  Gas  Engine  Cylinder. 

In  a  gas  or  gasoline-motor  with  a  small  clearance  or 
compression  space — with  high  compression — the  surface 
with  which  the  burning  gases  come  into  contact  is  much 
smaller  in  comparison  with  the  compression  space  in  a 
low-compression  motor.  Another  advantage  of  a  high- 
compression  motor  is  that  on  account  of  the  smaller  clear- 
ance of  combustion  space  less  cooling  water  is  required 
than  with  a  low-compression  motor,  as  the  temperature, 


70  Aviation  Engines 

and  consequently  the  pressure,  falls  more  rapidly.  The 
loss  of  heat  through  the  water-jacket  is  thus  less  in  the 
case  of  a  high-compression  than  in  that  of  a  low-compres- 
sion motor.  In  the  non-compression  type  of  motor  the 
best  results  were  obtained  with  a  charge  of  16  to  18  parts 
of  gas  and  100  parts  of  air,  while  in  the  compression  type 
the  best  results  are  obtained  with  an  explosive  mixture 
of  7  to  10  parts  of  gas  and  100  parts  of  air,  thus  showing 
that  by  the  utilization  of  compression  a  weaker  charge 
with  a  greater  thermal  efficiency  is  permissible. 

It  has  been  found  that  the  explosive  pressure  resulting 
from  the  ignition  of  the  charge  of  gas  or  gasoline-vapor 
and  air  in  the  gas-engine  cylinder  is  about  4^  times  the 
pressure  prior  to  ignition.  The  difficulty  about  getting 
high  compression  is  that  if  the  pressure  is  too  high  the 
charge  is  likely  to  ignite  prematurely,  as  compression 
always  results  in  increased  temperature.  The  cylinder 
may  become  too  hot,  a  deposit  of  carbon,  a  projecting 
electrode  or  plug  body  in  the  cylinder  may  become  in- 
candescent and  ignite  the  charge  which  has  been  exces- 
sively heated  by  the  high  compression  and  mixture  of 
the  hot  gases  of  the  previous  explosion. 

FACTORS  LIMITING  COMPRESSION 

With  gasoline-vapor  and  air  the  compression  should  not 
be  raised  above  about  90  to  95  pounds  to  the  square  inch, 
many  manufacturers  not  going  above  65  or  70  pounds. 
For  natural  gas  the  compression  pressure  may  easily  be 
raised  to  from  85  to  100  pounds  per  square  inch.  For 
gases  of  low  calorific  value,  such  as  blast-furnace  or  pro- 
ducer-gas, the  compression  may  be  increased  to  from  140 
to  190  pounds.  In  fact  the  ability  to  raise  the  compres- 
sion to  a  high  point  with  these  gases  is  one  of  the  prin- 
cipal reasons  for  their  successful  adoption  for  gas-engine 
use.  In  kerosene  injection  engines  the  compression  of  250 
pounds  per  square  inch  has  been  used  with  marked  econ- 
omy. Many  troubles  in  regard  to  loss  of  power  and  in- 
crease of  fuel  have  occurred  and  will  no  doubt  continue, 


Factors  Limiting  Compression 


71 


owing  to  the  wear  of  valves,  piston,  and  cylinder,  which 
produces  a  loss  in  compression  and  explosive  pressure 
and  a  waste  of  fuel  by  leakage.  Faulty  adjustment  of 
valve  movement  is  also  a  cause  of  loss  of  power;  which 
may  be  from  tardy  closing  of  the  inlet-valve  or  a  too  early 
opening  of  the  exhaust-valve. 

The  explosive  pressure  varies  to  a  considerable  amount 
in  proportion  to  the  compression  pressure  by  the  differ- 
ence in  fuel  value  and  the  proportions  of  air  mixtures, 
so  that  for  good  illuminating  gas  the  explosive  pressure 
may  be  from  2.5  to  4  times  the  compression  pressure. 
For  natural  gas  3  to  4.5,  for  gasoline  3  to  5,  for  producer- 
gas  2  to  3,  and  for  kerosene  by  injection  3  to  6. 

The  compression  temperatures,  although  well  known 
and  easily  computed  from  a  known  normal  temperature 
of  the  explosive  mixture,  are  subject  to  the  effect  of  the 
uncertain  temperature  of  the  gases  of  the  previous  ex- 
plosion remaining  in  the  cylinder,  the  temperature  of  its 
walls,  and  the  relative  volume  of  the  charge,  whether  full 
or  scant;  which  are  terms  too  variable  to  make  any  com- 
putations reliable  or  available. 

For  the  theoretical  compression  temperatures  from  a 
known  normal  temperature,  we  append  a  table  of  the  rise 
in  temperature  for  the  compression  pressures  in  the  fol- 
lowing table: 

TABLE  IV. — COMPRESSION  TEMPERATURES  FROM  A  NORMAL  TEMPERATURE  OF 
60  DEGREES  FAHRENHEIT 


100  Ibs.  gauge . 484° 

90  Ibs.  gauge 459° 

80  Ibs.  gauge 433° 

70  Ibs.  gauge 404° 


60  Ibs.  gauge 373° 

50  Ibs.  gauge. . 339° 

40  Ibs.  gauge 301° 

30  Ibs.  gauge 258° 


CHART    FOR    DETERMINING    COMPRESSION    PRESSURES 

A  very  useful  chart  (Fig.  16)  for  determining  com- 
pression pressures  in  gasoline-engine  cylinders  for  vari- 
ous ratios  of  compression  space  to  total  cylinder  volume 
is  given  by  P.  S.  Tice,  and  described  in  the  Chilton  Au- 
tomobile Directory  by  the  originator  as  follows: 


72 


Aviation  Engines 


It  is  many  times  desirable  to  have  at  hand  a  conve- 
nient means  for  at  once  determining  with  accuracy  what 
the  compression  pressure  will  be  in  a  gasoline-engine  cyl- 
inder, the  relationship  between  the  volume  of  the  com- 
pression space  and  the  total  cylinder  volume  or  that  swept 
by  the  piston  being  known.  The  curve  at  Fig.  16  is 
offered  as  such  a  means.  It  is  based-  on  empirical  data 


Fig.  16. — Chart  Showing  Relation  Between  Compression  Volume 
and  Pressure. 

gathered  from  upward  of  two  dozen  modern  automobile 
engines  and  represents  what  may  be  taken  to  be  the  results 
as  found  in  practice.  It  is  usual  for  the  designer  to  find 
compression  pressure  values,  knowing  the  volumes  from 
the  equation 


which  is  for  adiabatic  compression  of  air.     Equation  (1) 
is  right  enough  in  general  form  but  gives  results  which 


Determining  Compression  Pressures  73 

are  entirely  too  high,  as  almost  all  designers  know  from 
experience.  The  trouble  lies  in  the  interchange  of  heat 
between  the  compressed  gases  and  the  cylinder  walls,  in 
the  diminution  of  the  exponent  (1.4  in  the  above)  due  to  the 
lesser  ratio  of  specific  heat  of  gasoline  vapor  and  in  the 
transfer  of  heat  from  the  gases  which  are  being  com- 
pressed to  whatever  fuel  may  enter  the  cylinder  in  an 
unvaporized  condition.  Also,  there  is  always  some  piston 
leakage,  and,  if  the  form  of  the  equation  (1)  is  to  be 
retained,  this  also  tends  to  lower  the  value  of  the  ex- 
ponent. From  experience  with  many  engines,  it  appears 
that  compression  reaches  its  highest  value  in  the  cylinder 
for  but  a  short  range  of  motor  speeds,  usually  during  the 
mid-range.  Also,  it  appears  that,  at  those  speeds  at  which 
compression  shows  its  highest  values,  the  initial  pressure 
at  the  start  of  the  compression  stroke  is  from  .5  to  .9  Ib. 
below  atmospheric.  Taking  this  latter  loss  value,  which 
shows  more  often  than  those  of  lesser  value,  the  compres- 
sion is  seen  to  start  from  an  initial  pressure  of  13.9  Ibs. 
per  sq.  in.  absolute. 

Also,  experiment  shows  that  if  the  exponent  be  given 
the  value  1.26,  instead  of  1.4,  the  equation  will  embrace 
all  heat  losses  in  the  compressed  gas,  and  compensate  for 
the  changed  ratio  of  specific  heats  for  the  mixture  and 
also  for  all  piston  leakage,  in  the  average  engine  with 
rings  in  good  condition  and  tight.  In  the  light  of  the 
foregoing,  and  in  view  of  results  obtained  from  its  use, 
the  above  curve  is  offered  —  values  of  P2  being  found 
from  the  equation 

/VA1'26 

P2  =  13.8  (~J 

In  using  this  curve  it  must  be  remembered  that  press- 
ures are  absolute..  Thus:  suppose  it  is  desired  to  know 
the  volumetric  relationships  of  the  cylinder  for  a  com- 
pression pressure  of  75  Ibs.  gauge.  Add  atmospheric 
pressure  to  the  desired  gauge  pressure  14.7  +  75  =  89.7 
Ibs.  absolute.  Locate  this  pressure  on  the  scale  of  ordi- 


74  Aviation  Engines 

nates  and  follow  horizontally  across  to  the  curve  and  then 
vertically  downward  to  the  scale  of  abscissas,  where  the 
ratio  of  the  combustion  chamber  volume  to  the  total  cyl- 
inder volume  is  given,  which  latter  is  equal  to  the  sum  of 
the  combustion  chamber  volume  and  that  of  the  piston 
sweep.  In  the  above  case  it  is  found  that  the  combustion 
space  for  a  compression  pressure  of  75  Ibs.  gauge  will  be 
.225  of  the  total  cylinder  volume,  or  .225  -~  775  =  .2905 
of  the  piston  sweep  volume.  Conversely,  knowing  the 
volumetric  ratios,  compression  pressure  can  be  read  di- 
rectly by  proceeding  from  the  scale  of  abscissas  verti- 
cally to  the  curve  and  thence  horizontally  to  the  scale  of 
ordinates. 

CAUSES  OF  HEAT  LOSS  AND  INEFFICIENCY  IN  EXPLOSIVE  MOTORS 

The  difference  realized  in  the  practical  operation  of 
an  internal  combustion  heat  engine  from  the  computed 
effect  derived  from  the  values  of  the  explosive  elements 
is  probably  the  most  serious  difficulty  that  engineers  have 
encountered  in  their  endeavors  to  arrive  at  a  rational 
conclusion  as  to  where  the  losses  were  located,  and  the 
ways  and  means  of  design  that  would  eliminate  the  causes 
of  loss  and  raise  the  efficiency  step  by  step  to  a  reason- 
able percentage  of  the  total  efficiency  of  a  perfect  cycle. 

An  authority  on  the  relative  condition  of  the  chemical 
elements  under  combustion  in  closed  cylinders  attributes 
the  variation  of  temperature  shown  in  the  fall  of  the  ex- 
pansion curve,  and  the  suppression  or  retarded  evolution 
of  heat,  entirely  to  the  cooling  action  of  the  cylinder  walls, 
and  to  this  nearly  all  the  phenomena  hitherto  obscure  in 
the  cylinder  of  a  gas-engine.  Others  attribute  the  great 
difference  between  the  theoretical  temperature  of  combus- 
tion and  the  actual  temperature  realized  in  the  practical 
operation  of  the  gas-engine,  a  loss  of  more  than  one-half 
of  the  total  heat  energy  of  the  combustibles,  partly  to  the 
dissociation  of  the  elements  of  combustion  at  extremely 
high  temperatures  and  their  reassociation  by  expansion 
in  the  cylinder,  to  account  for  the  supposed  continued 


Causes  of  Heat  Loss 


75 


combustion  and  extra  adiabatic  curve  of  the  expansion 
line  on  the  indicator  card. 

The  loss  of  heat  to  the  walls  of  the  cylinder,  piston, 
and  clearance  space,  as  regards  the  proportion  of  wall 
surface  to  the  volume,  has  gradually  brought  this  point 


Fig.  17. — The  Thompson  Indicator,   an  Instrument  for  Determining  Com- 
pressions and  Explosion  Pressure  Values  and  Recording  Them  on  Chart. 

to  its  smallest  ratio  in  the  concave  piston-head  and  glob- 
ular cylinder-head,  with  the  smallest  possible  space  in  the 
inlet  and  exhaust  passage.  The  wall  surface  of  a  cylin- 
drical clearance  space  or  combustion  chamber  of  one-half 
its  unit  diameter  in  length  is  equal  to  3.1416  square  units, 
its  volume  but  0.3927  of  a  cubic  unit ;  while  the  same  wall 


76  Aviation  Engines 

surface  in  a  spherical  form  has  a  volume  of  0.5236  of  a 
cubic  unit.  It  will  be  readily  seen  that  the  volume  is  in- 
creased 33%  per  cent,  in  a  spherical  over  a  cylindrical 
form  for  equal  wall  surfaces  at  the  moment  of  explosion, 
when  it  is  desirable  that  the  greatest  amount  of  heat  is 
generated,  and  carrjdng  with  it  the  greatest  possible  press- 
ure from  which  the  expansion  takes  place  by  the  movement 
of  the  piston. 

The  spherical  form  cannot  continue  during  the  stroke 
for  mechanical  reasons;  therefore  some  proportion  of 
piston  stroke  of  cylinder  volume  must  be  found  to  cor- 
respond with  a  spherical  form  of  the  combustion  chamber 
to  produce  the  least  loss  of  heat  through  the  walls  during 


Fig.  18. — Spherical  Combustion 
Chamber. 


Fig.  19. — Enlarged  Combustion 
Chamber. 


the  combustion  and  expansion  part  of  the  stroke.  This 
idea  is  illustrated  in  Figs.  18  and  19,  showing  how  the 
relative  volumes  of  cylinder  stroke  and  combustion  cham- 
ber may  be  varied  to  suit  the  requirements  due  to  the 
quality  of  the  elements  of  combustion. 

Although  the  concave  piston-head  shows  economy  in 
regard  to  the  relation  of  the  clearance  volume  to  the  wall 
area  at  the  moment  of  explosive  combustion,  it  may  be 
clearly  seen  that  its  concavity  increases  its  surface  area 
and  its  capacity  for  absorbing  heat,  for  which  there  is 
no  provision  for  cooling  the  piston,  save  its  contact  with 
the  walls  of  the  cylinder  and  the  slight  air  cooling  of  its 
back  by  its  reciprocal  motion.  For  this  reason  the  con- 
cave piston-head  has  not  been  generally  adopted  and  the 
concave  cylinder-head,  as  shown  in  Fig.  19,  with  a  flat 


Mercedes  Aviation  Engine 


77 


Inlet  Valve 


Exhaust 

Valve 


Concave. 
Piston  Top 


,,~  Approximately 
Spherical 
Chamber 


.-Carburetor 


^Connecting 
Rod 


" OH  Sump 


Fig.    20. — Mercedes  Aviation  Engine   Cylinder   Section    Showing  Approximately 
Spherical  Combustion    Chamber    and    Concave   Piston  Top. 


78  Aviation  Engines 

piston-head  is  the  latest   and  best   practice   in   airplane 
engine   construction. 

The  practical  application  of  the  principle  just  outlined 
to  one  of  the  most  efficient  airplane  motors  ever  designed, 
the  Mercedes,  is  clearly  outlined  at  Fig.  20. 


HEAT  LOSSES   TO    COOLING  WATER 

The  mean  temperature  of  the  wall  surface  of  the  com- 
bustion chamber  and  cylinder,  as  indicated  by  the  tem- 
peratures of  the  circulating  water,  has  been  found  to  be 
an  important  item  in  the  economy  of  the  gas-engine. 
Dugald  Clerk,  in  England,  a  high  authority  in  practical 
work  with  the  gas-engine,  found  that  10  per  cent,  of  the 
gas  for  a  stated  amount  of  power  was  saved  by  using 
water  at  a  temperature  in.  which  the  ejected  water  from 
the  cylinder- jacket  was  near  the  boiling-point,  and  ven- 
tures the  opinion  that  a  still  higher  temperature  for  the 
circulating  water  may  be  used  as  a  source  of  economy. 
This  could  be  made  practical  in  the  case  of  aviation  en- 
gines by  adjusting  the  air-cooling  surface  of  the  radiator 
so  as  to  maintain  the  inlet  water  at  just  below  the  boiling 
point,  and  by  the  rapid  circulation  induced  by  the  pump 
pressure,  to  return  the  water  from  the  cylinder- jacket  a 
few  degrees  above  the  boiling  point.  The  thermal  dis- 
placement systems  of  cooling  employed  in  automobiles 
are  working  under  more  favorable  temperature  conditions 
than  those  engines  in  which  cooling  is  more  energetic. 

For  a  given  amount  of  heat  taken  from  the  cylinder 
by  the  largest  volume  of  circulating  water,  the  difference 
in  temperature  between  inlet  and  outlet  of  the  water1 
jacket  should  be  the  least  possible,  and  this  condition  of 
the  water  circulation  gives  a  more  even  temperature  to 
all  parts  of  the  cylinder;  while,  on  the  contrary,  a  cold- 
water  supply,  say  at  60°  F.,  so  slow  as  to  allow  the  ejected 
water  to  flow  off  at  a  temperature  near  the  boiling-point, 
must  make  a  great  difference  in  temperature  between  the 
bottom  and  top  of  the  cylinder,  with  a  loss  in  economy 


Heat  Losses  to  Cooling  Water  79 

in  gas  and  other  fuels,  as  well  as  in  water,  if  it  is  ob- 
tained by  measurement. 

From  the  foregoing  considerations  of  losses  and  ineffi- 
ciencies, we  find  that  the  practice  in  motor  design  and 
construction  has  not  yet  reached  the  desired  perfection 
in  its  cycular  operation.  Step  by  step  improvements  have 
been  made  with  many  changes  in  design  though  many 
.have  been  without  merit  as  an  improvement,  farther  than 
to  gratify  the  longings  of  designers  for  something  dif- 
ferent from  the  other  thing,  'and  to  establish  a  special 
construction  of  their  own.  These  efforts  may  in  time 
produce  a  motor  of  normal  or  standard  design  for  each 
kind  of  fuel  that  will  give  the  highest  possible  efficiency 
for  all  conditions  of  service. 


CHAPTER   IV 

Engine  Parts  and  Functions — Why  Multiple  Cylinder  Engines  Are 
Best — Describing  Sequence  of  Operations — Simple  Engines — Four 
and  Six  Cylinder  Vertical  Tandem  Engines — Eight  and  Twelve 
Cylinder  V  Engines — Radial  Cylinder  Arrangement — Rotary  Cylin- 
der Forms. 

ENGINE    PARTS    AND    FUNCTIONS 

THE  principal  elements  of  a  gas  engine  are  not  diffi- 
cult to  understand  and  their  functions  are  easily  denned. 
In  place  of  the  barrel  of  the  gun  one  has  a  smoothly 
machined  cylinder  in  which  a  small  cylindrical  or  barrel- 
shaped  element  fitting  the  bore  closely  may  be  likened  to 
a  bullet  or  cannon  ball.  It  differs  in  this  important 
respect,  however,  as  while  the  shot  is  discharged  from 
the  mouth  of  the  cannon  the  piston  member  sliding  inside 
of  the  main  cylinder  cannot  leave  it,  as  its  movements 
back  and  forth  from  the  open  to  the  closed  end  and  back 
again  are  limited  by  simple  mechanical  connection  or  link- 
age which  comprises  crank  and  connection  rod.  It  is  by 
this  means  that  the  reciprocating  movement  of  the  piston 
is  transformed  into  a  rotary  motion  of  the  crank-shaft. 

The  fly-wheel  is  a  heavy  member  attached  to  the  crank- 
shaft of  an  automobile  engine  which  has  energy  stored 
in  its  rim  as  the  member  revolves,  and  the  momentum 
of  this  revolving  mass  tends  to  equalize  the  intermittent 
pushes  on  the  piston  head  produced  by  the  explosion  of 
the  gas  in  the  cylinder.  In  aviation  engines,  the  weight 
of  the  propeller  or  that  of  rotating  cylinders  themselves 
performs  the  duty  of  a  fly-wheel,  so  no  separate  member 
is  needed.  If  some  explosive  is  placed  in  the  chamber 
formed  by  the  piston  and  closed  end  of  the  cylinder  and 
exploded,  the  piston  would  be  the  only  part  that  would 
yield  to  the  pressure  which  would  produce  a  downward 
movement.  As  this  is  forced  down  the  crank-shaft  is 

80 


81 


82  Aviation  Engines 

turned  by  the  connecting  rod,  and  as  this  part  is  hinged 
at  both  ends  it  is  free  to  oscillate  as  the  crank  turns,  and 
thus  the  piston  may  slide  back  and  forth  while  the  crank- 
shaft is  rotating  or  describing  a  curvilinear  path. 

In  addition  to  the  simple  elements  described  it  is  evi- 
dent that  a  gasoline  engine  must  have  other  parts.  The 
most  important  of  these  are  the  valves,  of  which  there  are 
generally  two  to  each  cylinder.  One  closes  the  passage 
connecting  to  the  gas  supply  and  opens  during  one  stroke 
of  the  piston  in  order  to  let  the  explosive  gas  into  the 
combustion  chamber.  The  other  member,  or  exhaust 
valve,  serves  as  a  cover  for  the  opening  through  which 
the  burned  gases  can  leave  the  cylinder  after  their  work 
is  done.  The  spark  plug  is  a  simple  device  which  may 
be  compared  to  the  fuse  or  percussion  cap  of  the  cannon. 
It  permits  one  to  produce  an  electric  spark  in  the  cyl- 
inder when  the  piston  is  at  the  best  point  to  utilize  the 
pressure  which  obtains  when  the  compressed  gas  is  fired. 
The  valves  are  open  one  at  a  time,  the  inlet  valve  being 
lifted  from  its  seat  while  -the  cylinder  is  filling  and  the 
exhaust  valve  is  opened  when  the  cylinder  is  being  cleared. 
They  are  normally  kept  seated  by  means  of  compression 
springs.  In  the  simple  motor  shown  at  Fig.  5,  the  exhaust 
valve  is  operated  by  means  of  a  pivoted  bell  crank  rocked 
by  a  cam  which  turns  at  half  the  speed  of  the  crank-shaft. 
The  inlet  valve  operates  automatically,  as  will  be  ex- 
plained in  proper  sequence. 

In  order  to  obtain  a  perfectly  tight  combustion  cham- 
ber, both  intake  and  exhaust  valves  are  closed  before  the 
gas  is  ignited,  because  all  of  the  pressure  produced  by 
the  exploding  gas  is  to  be  directed  against  the  top  of 
the  movable  piston.  When  the  piston  reaches  the  bottom 
of  its  power  stroke,  the  exhaust  valve  is  lifted  by  means 
of  the  bell  crank  which  is  rocked  because  of  the  point  or 
lift  on  the  cam.  The  cam-shaft  is  driven  by  positive 
gearing  and  revolves  at  half  the  engine  speed.  The  ex- 
haust valve  remains  open  during  the  whole  of  the  return 
stroke  of  the  piston,  and  as  this  member  moves  toward 


Why  Multiple  Cylinder  Forms  Are  Best         83 

the  closed  end  of  the  cylinder  it  forces  out  burned  gases 
ahead  of  it,  through  the  passage  controlled  by  the  exhaust 
valve.  The  cam-shaft  is  revolved  at  half  the  engine  speed 
because  the  exhaust  valve  is  raised  from  its  seat  during 
only  one  stroke  out  of  four,  or  only  once  every  two  revo- 
lutions. Obviously,  if  the  cam  was  turned  at  the  same 
speed  as  the  crank-shaft  it  would  remain  open  once  every 
revolution,  whereas  the  burned  gases  are  expelled  from 
the  individual  cylinders  only  once  in  two  turns  of  the 
crank-shaft. 

WHY   MULTIPLE    CYLINDER   FORMS  ARE   BEST 

Owing  to  the  vibration  which  obtains  from  the  heavy 
explosion  in  the  large  single-cylinder  engines  used  for 
stationary  power  other  forms  were  evolved  in  which  the 
cylinder  was  smaller  and  power  obtained  by  running  the 
engine  faster,  but  these  are  suitable  only  for  very  low 
powers. 

When  a  single-cylinder  engine  is  employed  a  very 
heavy  fly-wheel  is  needed  to  carry  the  moving  parts 
through  idle  strokes  necessary  to  obtain  a  power  im- 
pulse. For  this  reason  automobile  and  aircraft  design- 
ers must  use  more  than  one  cylinder,  and  the  tendency 
is  to  produce  power  by  frequently  occurring  light  im- 
pulses rather  than  by  a  smaller  number  of  explosions 
having  greater  force.  "When  a  single-cylinder  motor  is 
employed  the  construction  is  heavier  than  is  needed  with 
a  multiple-cylinder  form.  Using  two  or  more  cylinders 
conduces  to  steady  power  generation  and  a  lessening  of 
vibration.  Most  modern  motor  cars  employ  four-cylinder 
engines  because  a  power  impulse  may  be  secured  twice 
every  revolution  of  the  crank-shaft,  or  a  total  of  four- 
power  strokes  during  two  revolutions.  The  parts  are  so 
arranged  that  while  the  charge  of  gas  in  one  cylinder  is 
exploding,  those  which  come  next  in  firing  order  are  com- 
pressing, discharging  the  inert  gases  and  drawing  in  a 
fresh  charge  respectively.  When  the  power  stroke  is 
completed  in  one  cylinder,  the  piston  in  that  member  in 


84  Aviation  Engines 

which  a  charge  of  gas  has  just  been  compressed  has 
reached  the  top  of  its  stroke  and  when  the  gas  is  ex- 
ploded the  piston  is  reciprocated  and  keeps  the  crank- 
shaft turning.  When  a  multiple-cylinder  engine  is  used 
the  fly-wheel  can  be  made  much  lighter  than  that  of  the 
simpler  form  and  eliminated  altogether  in  some  designs. 
In  fact,  many  modern  multiple-cylinder  engines  develop- 
ing  300  horse-power  weigh  less  than  the  early  single-  and 
double-cylinder  forms  which  developed  but  one-tenth  or 
one-twentieth  that  amount  of  energy. 

DESCRIBING    SEQUENCE    OF    OPERATIONS 

Eef erring  to  Fig.  22,  A,  the  sequence  of  operation  in 
a  single-cylinder  motor  can  be  easily  understood.  As- 
suming that  the  crank-shaft  is  turning  in  the  direction 
of  the  arrow,  it  will  be  seen  that  the  intake  stroke  comes 
first,  then  the  compression,  which  is  followed  by  the  power 
impulse,  and  lastly  the  exhaust  stroke.  If  two  cylinders 
are  used,  it  is  possible  to  balance  the  explosions  in  such 
a  way  that  one  will  occur  each  revolution.  This  is  true 
with  either  one  of  two  forms  of  four-cycle  motors.  At 
B,  a  two-cylinder  vertical  engine  using  a  crank- shaft  in 
which  the  crank-pins  are  on  the  same  plane  is  shown. 
The  two  pistons  move  up  and  down  simultaneously.  Be- 
f erring  to  the  diagram  describing  the  strokes,  and  assum- 
ing that  the  outer  circle  represents  the  cycle  of  operations 
in  one  cylinder  while  the  inner  circle  represents  the  se- 
quence of  events  in  the  other  cylinder,  while  cylinder 
No.  1  is  taking  in  a  fresh  charge  of  gas,  cylinder  No.  2 
is  exploding.  When  cylinder  No.  1  is  compressing,  cyl- 
inder No.  2  is  exhausting.  During  the  time  that  the  charge 
in  cylinder  No.  1  is  exploded,  cylinder  No.  2  is  being  filled 
with  fresh^gas.  While  the  exhaust  gases  are  being  dis- 
charged from  cylinder  No.  1,  cylinder  No.  2  is  compressing 
the  gas  previously  taken. 

The  same  condition  obtains  when  the  crank-pins  are 
arranged  a.t  one  hundred  and  eighty  degrees  and  the  cyl- 
inders are  opposed,  as  shown  at  C.  The  reason  that  the 


Sequence  of  Operations 


85 


y 

Single  Cylinder 


HPU 


Two  Cylinder  Vertical 
Cranhpins  on  Same  Plans 


Two  Cylinder,  Opposed 
Crmnhpins  At  180  Degrees 


Fig.  22. — Diagrams  Illustrating  Sequence  of  Cycles  in  One-  and  Two-Cylinder 
Engines  Showing  More  Uniform  Turning  Effort  on  Crank-Shaft  with 
Two-Cylinder  Motors. 


86  Aviation  Engines 

two-cylinder  opposed  motor  is  more  popular  than  that 
having  two  vertical  cylinders  is  that  it  is  difficult  to  bal- 
ance the  construction  shown  at  B,  so  that  the  vibration 
will  not  be  excessive.  The  two-cylinder  opposed  motor 
has  much  less  vibration  than  the  other  form,  and  as  the 
explosions  occur  evenly  and  the  motor  is  a  simple  one 
to  construct,  it  has  been  very  popular  in  the  past  on 
light  cars  and  has  received  limited  application  on  some 
early,  light  airplanes. 

To  demonstrate  very  clearly  the  advantages  of  multi- 
ple-cylinder engines  the  diagrams  at  Fig.  23  have  been 
prepared.  At  A,  a  three-cylinder  motor,  having  crank- 
pins  at  one  hundred  and  twenty  degrees,  which  means  that 
they  are  spaced  at  thirds  of  the  circle,  we  have  a  form 
of  construction  that  gives  a  more  even  turning  than  that 
possible  with  -a  two-cylinder  engine.  Instead  of  one  ex- 
plosion per  revolution  of  the  crank-shaft,  one  will  obtain 
three  explosions  in  two  revolutions.  The  manner  in  which 
the  explosion  strokes  occur  and  the  manner  they  overlap 
strokes  in  the  other  cylinder  is  shown  at  A.  Assuming 
that  the  cylinders  fire  in  the  following  order,  first  No.  1, 
then  No.  2,  and  last  No.  3,  we  will  see  that  while  cylinder 
No.  1,  represented  by  the  outer  circle,  is  on  the  power 
stroke,  cylinder  No.  3  has  completed  the  last  two-thirds 
of  its  exhaust  stroke  and  has  started  on  its  intake  stroke. 
Cylinder  No.  2,  represented  by  the  middle  circle,  during 
this  same  period  has  completed  its  intake  stroke  and  two- 
thirds  of  its  compression  stroke.  A  study  of  the  diagram 
will  show  that  there  is  an  appreciable  lapse  of  time  be- 
tween each  explosion. 

Three-cylinder  engines  are  not  used  on  aircraft  at  the 
present  time,  though  Bleriot's  flight  across  the  British 
Channel  was  made  with  a  three-cylinder  Anzani  motor. 
It  was  not  a  conventional  form,  however.  The  three-cyl- 
inder engine  is  practically  obsolete  at  this  time  for  any 
purpose  except  "penguins"  or  school  machines  that  are 
incapable  of  flight  and  which  are  used  in  some  French 
training  schools  for  aviators. 


Four-  and  Six -Cylinder  Engines 


87 


Firing  Order  1,3,2 


7 
Three  Cylinder,  Cranks  At  120  Degrees 


Firing  Order  J. 2,4,3 


Four  Cylinder,  Cranhs  At  180  Degrees 


First  Revolution 
78(T          180 


Second  Revolution 
780°  780° 


Fig.  23.— Diagrams  Demonstrating  Clearly  Advantages  which  Obtain  when 
Multiple-Cylinder  Motors  are  Used  as  Power  Plants. 


88  Aviation  Engines 


FOUR-     AND     SIX-CYLINDER     ENGINES 

In  the  four-cylinder  engine  operation  which  is  shown 
at  Fig.  23,  B,  it  will  be  seen  that  the  power  strokes  follow 
each  other  without  loss  of  time,  and  one  cylinder  begins 
to  fire  and  the  piston  moves  down  just  as  soon  as  the 
member  ahead  of  it  has  completed  its  power  stroke.  In 
a  four-cylinder  motor,  the  crank-pins  are  placed  at  one 
hundred  and  eighty  degrees,  or  on  the  halves  of  the  crank 
circle.  The  crank-pins  for  cylinders  No.  1  and  No.  4  are 
on  the  same  plane,  while  those  for  cylinders  No.  2  and 
No.  3  also  move  in  unison.  The  diagram  describing  se- 
quence of  operations  in  each  cylinder  is  based  on  a  firing 
order  of  one,  two,  four,  three.  The  outer  circle,  as  in 
previous  instances,  represents  the  cycle  of  operations  in 
cylinder  one.  The  next  one  toward  the  center,  cylinder 
No.  2,  the  third  circle  represents  the  sequence  of  events 
in  cylinder  No.  3,  while  the  inner  circle  outlines  the  strokes 
in  cylinder  four.  The  various  cylinders  are  working  as 
follows : 

1.  2.  3.  4. 

Explosion        Compression  Exhaust  Intake 

Exhaust  Explosion        Intake  Compression 

Intake  Exhaust  Compression  Explosion 

Compression  Intake  Explosion  Exhaust 

It  will  be  obvious  that  regardless  of  the  method  of 
construction,  or  the  number  of  cylinders  employed,  ex- 
actly the  same  number  of  parts  must  be  used  in  each 
cylinder  assembly  and  one  can  conveniently  compare 
any  multiple-cylinder  power  plant  as  a  series  of  single- 
cylinder  engines  joined  one  behind  the  other  and  so 
coupled  that  one  will  deliver  power  and  produce  useful 
energy  at  the  crank-shaft  where  the  other  leaves  off. 
The  same  fundamental  laws  governing  the  action  of  a 
single  cylinder  obtain  when  a  number  are  employed,  and 
the  sequence  of  operation  is  the  same  in  all  members,  ex- 
cept that  the  necessary  functions  take  place  at  different 


Why  Multiple  Cylinder  Forms- Are  Best         89 

times.  If,  for  instance,  all  the  cylinders  of  a  four-cylin- 
der motor  were  fired  at  the  same  time,  one  would  obtain 
the  same  effect  as  though  a  one-piston  engine  was  used, 
which  had  a  piston  displacement  equal  to  that  of  the  four 
smaller  members.  As  is  the  case  with  a  single-cylinder 
engine,  the  motor  would  be  out  of  correct  mechanical  bal- 
ance because  all  the  connecting  rods  would  be  placed  on 
crank-pins  that  lie  in  the  same  plane.  A  very  large  fly- 
wheel would  be  necessary  to  carry  the  piston  through  the 
idle  strokes,  and  large  balance  weights  would  be  fitted  to 
the  crank-shaft  in  an  effort  to  compensate  for  the  weight 
of  the  four  pistons,  and  thus  reduce  vibratory  stresses 
which  obtain  when  parts  are  not  in  correct  balance. 

There  would  be  no  advantage  gained  by  using  four 
cylinders  in  this  manner,  and  there  would  be  more  loss  of 
heat  and  more  power  consumed  in  friction  than  in  a  one- 
piston  motor  of  the  same  capacity.  This  is  the  reason 
that  when  four  cylinders  are  used  the  arrangement  of 
crank-pins  is  always  as  shown  at  Fig.  23,  B — i.e.,  two 
pistons  are  up,  while  the  other  two  are  at  the  bottom  of 
the  stroke.  With  this  construction,  we  have  seen  that  it 
is  possible  to  string  out  the  explosions  so  that  there  will 
always  be  one  cylinder  applying  power  to  the  crank-shaft. 
The  explosions  are  spaced  equally.  The  parts  are  in 
correct  mechanical  balance  because  two  pistons  are  on  the 
upstroke  while  the  other  two  are  descending.  Care  is 
taken  to  have  one  set  of  moving  members  weigh  exactly 
the  same  as  the  other.  With  a  four-cylinder  engine  one 
has  correct  balance  and  continuous  application  of  energy. 
This  insures  a  smoother  running  motor  which  has  greater 
efficiency  than  the  simpler  one-,  two-,  and  three-cylinder 
forms  previously  described.  Eliminating  the  stresses 
which  would  obtain  if  we  had  an  unbalanced  ftiechanism 
and  irregular  power  application  makes  for  longer  life. 
Obviously  a  large  number  of  relatively  light  explosions 
will  produce  less  wear  and  strain  than  would  a  lesser 
number  of  powerful  ones.  As  the  parts  can  be  built  lighter 
if  the  explosions  are  not  heavy,  the  engine  can  be  oper- 


90 


Aviation  Engines 


ated  at  higher  rotative  speeds  than  when  large  and  cum- 
bersome members  are  utilized.  Four-cylinder  engines 
intended  for  aviation  work  have  been  built  according  to 
the  designs  shown  at  Fig.  24,  but  these  forms  are  un- 
conventional and  seldom  if  ever  used. 

The  six-cylinder  type  of  motor,  the  action  of  which  is 
shown  at  Fig.  23,  C,  is  superior  to  the  four-cylinder,  inas- 


Radial  Cylinder 
Arrangement 


Two  Sets  of  Opposed  Cylinders 


Fig.  24. — Showing  Three  Possible  Though  Unconventional  Arrangements  of 
Four-Cylinder  Engines. 

much  as  the  power  strokes  overlap,  and  instead  of  having 
two  explosions  each  revolution  we  have  three  explosions. 
The  conventional  crank-shaft  arrangement  in  a  six-cylinder 
engine  is  just  the  same  as  though  one  used  two  three- 
cylinder  shafts  fastened  together,  so  pistons  1  and  6  are 
on  the  same  plane  as  are  pistons  2  and  5.  Pistons  3  and 
4  also  travel  together.  With  the  cranks  arranged  as  out- 
lined at  Fig.  23,  C,  the  firing  order  is  one,  five,  three,  six, 
two,  four.  The  manner  in  which  the  power  strokes  overlap 
is  clearly  shown  in  the  diagram.  An  interesting  com- 


Why  Multiple  Cylinder  Forms  Are  Best         91 


parison  is  also  made  in  the  diagrams  at  Fig.  25  and  in  the 
upper  corner  of  Fig.  23,  C. 

A  rectangle  is  divided  into  four  columns ;  each  of  these 
corresponds  to  one  hundred  and  eighty  degrees,  or  half  a 
revolution.  Thus  the  first  revolution  of  the  crank-shaft 
is  represented  by  the  first  two  columns,  while  the  second 
revolution  is  represented  by  the  last  two.  Taking  the  por- 


THE  APPLICATION   OF  POWER   IN   THE  SIX-CYLINDER   MOTOR 

£  rowCR  STBO«t  PDWtR  SIHOICl  P0*rn  SIIIOIIC  Kmt»  St«O«C  K>wf  «  SIKOHI  » 


"»4«EV. 


JSRE 


MV. 


IK#EV. 


1»REV.. 


2  REV. 


JK8&J83 

THE  APPLICATION  OF  POWER  IN  THE  FOUR-CYLINDER  MOTOR 

cmtTtst   Mtss  'rowtnst»oin  iou.  rowii  tnvivi  «w_.        .       POWCI  stuoy  iou  rowtn  v«o«c  wit 


7\ 


THIS  DIAGRAM  REPRESENTS  ONE  "CYCLE"  IN  WHICH  THE  PISTON  TRAVELS  20  INCHES 
MOTQR  «_n«a  REPRESENTS  POWER  I  I  REPRESENTS  NO  POWER 

\  CYL 
2  CYL. 


4  CYL 


6  CYL 


Fig.  25. — Diagrams  Outlining  Advantages  of  Multiple  Cylinder  Motors,  and 
Why  They  Deliver  Power  More  Evenly  Than  Single  Cylinder  Types. 

tion  of  the  diagram  which  shows  the  power  impulse  in  a 
one-cylinder  engine,  we  see  that  during  the  first  revolution 
there  has  been  no  power  impulse.  During  the  first  half 
of  the  second  revolution,  however,  an  explosion  takes  place 
and  a  power  impulse  is  obtained.  The  last  portion  of  the 
second  revolution  is  devoted  to-  exhausting  the  burned 
gases,  so  that  there  are  three  idle  strokes  and  but  one 
power  stroke.  The  effect  when  two  cylinders  are  employed 
is  shown  immediately  below. 


92 


Aviation  Engines 


Here  we  have  one  explosion  during  the  first  half  of  the 
first  revolution  in  one  cylinder  and  another  during  the  first 
half  of  the  second  revolution  in  the  other  cylinder.  "With 
a  four-cylinder  engine  there  is  an  explosion  each  half  revo- 
lution, while  in  a  six-cylinder  engine  there  is  one  and  one- 
half  explosions  during  each  half  revolution.  When  six 


Diagrams  Show incj  Duration  of  Eve nts 
for  a  Four  Stroke  Cycle. Six  Cylinder  Engine 

When    Fxhaus*  Valves  open  45° early 

and  clofe  7" late,  and  Inlet 

Valves  open  12° late  and 


Fig, 4 


No+e.-Read  Figs.  '3&4 
from  Centers  Outward 


1st  Str     2nd  Str    3rd  Str    4th  Str 


1st  Revolution 
720:-0° 


ONE    CYC  LE 


360' 


2nd    Revolution 


Fig. 3 


540* 


Fig.  26. — Diagrams  Showing  Duration  of  Events  for  a  Four-Stroke  Cycle, 

Six-Cylinder  Engine. 

cylinders  are  used  there  is  no  lapse  of  time  between  power 
impulses,  as  these  overlap*  and  a  continuous  and  smooth- 
turning  movement  is  imparted  to  the  crank  shaft.  The 
diagram  shown  at  Fig.  26,  prepared  by  E.  P.  Pulley,  can 
be  studied  to  advantage  in  securing  an  idea  of  the  coor- 
dination of  effort  that  takes  place  in  an  engine  of  the  six- 
cylinder  type. 


Actual  Duration  of  Cycle  Functions 


93 


ACTUAL   DURATION    OF   DIFFERENT    STROKES 

In  the  diagrams  previously  presented  the  writer  has 
assumed,  for  the  sake  of  simplicity,  that  each  stroke  takes 
place  during  half  of  one  revolution  of  the  crank-shaft, 


Inlet  Value 
Opens  l3^'Past 
Center-Upper, 


Exhaust  Value 
Closes  1^  Past 
Center-Upper 


Inlet  Valve 


Center-Lower 


Exhaust  Valve 
Opens  7"Before 
Center-Lower 


Fig.  27. — Diagram  Showing  Actual  Duration  of  Different  Strokes  in  Degrees. 

which  corresponds  to  a  crank-pin  travel  of  one  hundred 
and  eighty  degrees.  The  actual  duration  of  these  strokes 
is  somewhat  different.  For  example,  the  inlet  stroke  is 
usually  a  trifle  more  than  a  half  revolution,  and  the  exhaust 
is  always  considerably  more.  The  diagram  showing  the 
comparative  duration  of  the  strokes  is  shown  at  Fig.  27. 


94  Aviation  Engines 

The  inlet  valve  opens  ten  degrees  after  the  piston  starts 
to  go  down  and  remains  open  thirty  degrees  after  the 
piston  has  reached  the  bottom  of  its  stroke.  This  means 
that  the  suction  stroke  corresponds  to  a  crank-pin  travel 
of  two  hundred  degrees,  while  the  compression  stroke  is 
measured  by  a  movement  of  but  one  hundred  and  fifty 
degrees.  It  is  common  practice  to  open  the  exhaust  valve 
before  the  piston  reaches  the  end  of  the  power  stroke  so 
that  the  actual  duration  of  the  power  stroke  is  about  one 
hundred  and  forty  degrees,  while  the  exhaust  stroke  cor- 
responds to  a  crank-pin  travel  of  two  hundred  and  twenty- 
five  degrees.  In  this  diagram,  which  represents  proper 


Power  1  ^^g^g^^Exhaus 

\\Compression     \       •  Power <?  ^H  Exhaust 

ompression 

Lompressionm     U  Power  6 
CompressionlMl  UPower4^^f  Exhaust 


1 
Revolutions 

Fig.  28. — Another  Diagram  to  Facilitate  Understanding  Sequence  of 
Functions  in  Six-Cylinder  Engine. 

time  for  the  valves  to  open  arid  close,  the  dimensions  in 
inches  given  are  measured  on  the  fly-wheel  and  apply  only 
to  a  certain  automobile  motor.  If  the  fly-wheel  were 
smaller  ten  degrees  would  take  up  less  than  the  dimensions 
given,  while  if  the  fly-wheel  was  larger  a  greater  space  on 
its  circumference  would  represent  the  same  crank-pin 
travel.  Aviation  engines  are  timed  by  using  a  timing  disc 
attached  to  the  crank-shaft  as  they  are  not  provided  with 
fly-wheels.  Obviously,  the  distance  measured  in  inches 
will  depend  upon  the  diameter  of  the  disc,  though  the 
number  of  degrees  interval  would  not  change. 

EIGHT-  AND   TWELVE-CYLINDER   V   ENGINES 

Those  who  have  followed  the  development  of  the  gaso- 
line engine  will  recall  the  arguments  that  were  made  when 
the  six-cylinder  motor  was  introduced  at  a  time  that  the 


Vee  Engine  Advantages 


95 


four-cylinder  type  was  considered  standard.  The  arrival 
of  the  eight-cylinder  has  created  similar  futile  discussion 
of  its  practicability  as  this  is  so  clearly  established  as  to 
be  accepted  without  question.  It  has  been  a  standard 
power  plant  for  aeroplanes  for  many  years,  early  expo- 
nents having  been  the  Antoinette,  the  Woolsley,  the 
Kenault,  the  E.  N.  V.  in  Europe  and  the  Curtiss  in  the 
United  States. 

The  reason  the  V  type  shown  at  Fig.  29,  A  is  favored  is 
that  the  "all-in-line  form"  which  is  shown  at  Fig.  29,  B  is 


Fig.  29. — Types  of  Eight-Cylinder  Engines  Showing  the  Advantage  of  the 
V  Method  of  Cylinder  Placing. 

not  practical  for  aircraft  because  of  its  length.  Compared 
to  the  standard  four-cylinder  engine  it  is  nearly  twice  as 
long  and  it  required  a  much  stronger  and  longer  crank- 
shaft. It  will  be  evident  that  it  could  not  be  located  to 
advantage  in  the  airplane  fuselage.  These  undesirable 
factors  are  eliminated  in  the  V  type  eight-cylinder  motor, 
as  it  consists  of  two  blocks  of  four  cylinders  each,  so  ar- 
ranged that  one  set  or  block  is  at  an  angle  of  forty-five 
degrees  from  the  vertical  center  line  of  the  motor,  or  at 
an  angle  of  ninety  degrees  with  the  other  set.  This 
arrangement  of  cylinders  produces  a  motor  that  is  no 


96 


Aviation  Engines 


longer   than   a   four-cylinder   engine    of   half   the   power 
would  be. 

Apparently  there  is  considerable  misconception  as  to 
the  advantage  of  the  two  extra  cylinders  of  the  eight  as 
compared  with  the  six-cylinder.  It  should  be  borne  in  mind 
that  the  multiplication  in  the  number  of  cylinders  noticed 
since  the  early  days  of  automobile  development  has  not 
been  for  solely  increasing  the  power  of  the  engine,  but  to 
secure  a  more  even  turning  movement,  greater  flexibility 


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Comparative  torque  diagram*  of  four,  elx   and   eight-cylinder  motor*,   showing    Increaie    In    uniform  ty    with    added    cylinder! 

Fig.  30. — Curves  Showing  Torque  of  Various  Engine  Types  Demonstrate 
Graphically  Marked  Advantage  of  the  Eight-Cylinder  Type. 

and  to  eliminate  destructive  vibration.  The  ideal  internal 
combustion  motor  is  the  one  having  the  most  uniform  turn- 
ing movement  with  the  least  mechanical  friction  loss. 
Study  of  the  torque  outlines  or  plotted  graphics  shown 
at  Figs.  25  and  30  will  show  how  multiplication  of  cylinders 
will  produce  steady  power  delivery  due  to  overlapping 
impulses.  The  most  practical  form  would  be  that  which 
more  nearly  conforms  to  the  steady  running  produced  by 
a  steam  turbine  or  electric  motor.  The  advocates  of  the 
eight-cylinder  engine  bring  up  the  item  of  uniform  torque 


Vee  Engine  Advantages 


97 


as  one  of  the  most  important  advantages  of  the  eight- 
cylinder  design.  A  number  of  torque  diagrams  are  shown 
at  Fig.  30.  While  these  appear  to  be  deeply  technical, 
they  may  be  very  easily  followed  when  their  purpose  is 
explained.  At  the  top  is  shown  the  torque  diagram  of  a 
single-cylinder  motor  of  the  four-cycle  type.  The  high 


Fig.  31. — Diagrams  Showing  How  Increasing  Number  of  Cylinders  Makes 
for  More  Uniform  Power  Application. 

point  in  the  line  represents  the  period  of  greatest  torque 
or  power  generation,  and  it  will  be  evident  that  this  occurs 
early  in  the  first  revolution  of  the  crank-shaft.  Below  this 
diagram  is  shown  a  similar  curve  except  that  it  is  pro- 
duced by  a  four-cylinder  engine.  Inspection  will  show  that 
the  turning  moment  is  much  more  uniform  than  in  the 


98  Aviation  Engines 

single  cylinder;  similarly,  the  six-cylinder  diagram  is  an 
improvement  over  the  four,  and  the  eight-cylinder  diagram 
is  an  improvement  over  the  six-cylinder. 

The  reason  that  practically  continuous  torque  is  ob- 
tained in  an  eight-cylinder  engine  is  that  one  cylinder  fires 
every  ninety  degrees  of  crank-shaft  rotation,  and  as  each 
impulse  lasts  nearly  seventy-five  per  cent,  of  the  stroke, 
one  can  easily  appreciate  that  an  engine  that  will  give  four 
explosions  per  revolution  of  the  crank-shaft  will  run  more 
uniformly  than  one  that  gives  but  three  explosions  per 
revolution,  as  the  six-cylinder  does,  and  will  be  twice  as 
smooth  running  as  a  four-cylinder,  in  which  but  two  explo- 
sions occur  per  revolution  of  the  crank-shaft.  The  com- 
parison is  so  clearly  shown  in  graphical  diagrams  and  in 
Fig.  31  that  further  description  is  unnecessary. 

Any  eight-cylinder  engine  may  be  considered  a  "twin- 
four,"  twelve-cylinder  engines  may  be  considered  "twin 


sixes/ 


The  only  points  in  which  an  eight-cylinder  motor  dif- 
fers from  a  four-cylinder  is  in  the  arrangement  of  the 
connecting  rod,  as  in  many  designs  it  is  necessary  to  have 
two  rods  working  from  the  same  crank-pin.  This  difficulty 
is  easily  overcome  in  some  designs  by  staggering  the  cylin- 
ders and  having  the  two  connecting  rod  big  ends  of  con- 
ventional form  side  by  side  on  a  common  crank-pin.  In 
other  designs  one  rod  is  a  forked  form  and  works  on  the 
outside  of  a  rod  of  the  regular  pattern.  Still  another 
method  is  to  have  a  boss  just  above  the  main  bearing  on 
one  connecting  rod  to  which  the  lower  portion  of  the  con- 
necting rod  in  the  opposite  cylinder  is  hinged.  As  the 
eight-cylinder  engine  may  actually  be  made  lighter  than 
the  six-cylinder  of  equal  power,  it  is  possible  to  use  smaller 
reciprocating  parts,  such  as  pistons,  connecting  rods  and 
valve  gear,  and  obtain  higher  engine  speed  with  practically 
no  vibration.  The  firing  order  in  nearly  every  case  is  the 
same  as  in  a  four-cylinder  except  that  the  explosions  occur 
alternately  in  each  set  of  cylinders.  The  firing  order  of 
an  eight-cylinder  motor  is  apt  to  be  confusing  to  the 


100 


Aviation  Engines 


motorist,  especially  if  one  considers  that  there  are  eight 
possible  sequences.  The  majority  of  engineers  favor  the 
alternate  firing  from  side  to  side.  Firing  orders  will  be 
considered  in  proper  sequence. 

The  demand  of  aircraft  designers  for  more  power  has 
stimulated  designers  to  work  out  twelve-cylinder  motors. 


ft,      I 


Fig.  33. — The  Hall-Scott  Four-Cylinder  100  Horse-Power  Aviation  Motor. 

These  are  high-speed  motors  incorporating  all  recent  fea- 
tures of  design  in  securing  light  reciprocating  parts,  large 
valve  openings,  etc.  The  twelve-cylinder  motor  .incorpor- 
ates the  best  features  of  high-speed  motor  design  and  there 
is  no  need  at  this  time  to  discuss  further  the  pros  and  cons 
of  the  twelve-cylinder  versus  the  eight  or  six,  because  it 
is  conceded  by  all  that  there  is  the  same  degree  of  steady 
power  application  in  the  twelve  over  the  eight  as  there 
would  be  in  the  eight  over  the  six.  The  question  resolves 


Propeller  D 
Reduction 


Fig.  34. — Two  Views  of  the  Duesenberg  Sixteen  Valve  Four-Cylinder 
Aviation  Motor. 
101 


102        .  Aviation  Engines 

itself  into  ]ia\ixig  a  motor  of  high  power  that  will  run  with 
,  Epnmimn;vibr.atiofi  and  that  produces  smooth  action.  This 
is  well  shoxvn  by  diagrams  at  Fig.  31.  It  should  be  re- 
membered that  if  an  eight-cylinder  engine  will  give  four 
explosions  per  revolution  of  the  fly-wheel,  a  twelve-cylinder 
type  will  give  six  explosions  per  revolution,  and  instead 
of  the  impulses  coming  90  degrees  crank  travel  apart,  as 
in  the  case  of  the  eight-cylinder,  these  will  come  but  60 


Overhead  Cam  Shaft 

-Valves 
Cylinders 


'Starting 
Crank 


Oil  Sump 


Engine  Base 


Fig.  35. — The  Hall-Scott  Six-Cylinder  Aviation  Engine. 

degrees  of  crank  travel  apart  in  the  case  of  the  twelve- 
cylinder.  For  this  reason,  the  cylinders  of  a  twelve  are 
usually  separated  by  60  degrees  while  the  eight  has  the 
blocks  spaced  90  degrees  apart.  The  comparison  can  be 
easily  made  hy  comparing  the  sectional  views  of  Vee 
engines  at  Fig.  32.  When  one  realizes  that  the  actual 
duration  of  the  power  stroke  is  considerably  greater  than 
120  degrees  crank  travel,  it  will  be  apparent  that  the 
overlapping  of  explosions  must  deliver  a  very  uniform 
application  of  power.  Vee  engines  have  been  devised 


Radial  Cylinder  Arrangements 


103 


having  the  cylinders  spaced  but  45  degrees  apart,  but  the 
explosions  cannot  be  timed  at  equal  intervals  as  when  90 
degrees  separate  the  cylinder  center  lines. 

RADIAL    CYLINDER   ARRANGEMENTS 

"While  the  fixed  cylinder  forms  of  engines,  having  the 
cylinders  in  tandem  in  the  four-  and  six-cylinder  models 
as  shown  at  Figs.  33  to  35  inclusive  and  the  eight-cylinder 
V  types  as  outlined  at  Figs.  36  and  37  have  been  generally 
used  and  are  most  in  favor  at  the  present  time,  other  forms 
of  motors  having  unconventional  cylinder  arrangements 
have  been  devised,  though  most  of  these  are  practically 


View  of  Power  Delivery  End 


Fig.  36. — The  Curtiss  Eight-Cylinder,  200.  Horse-Power  Aviation  Engine. 


102 


Aviation  Engines 


itself  into  lia\ing  a  motor  of  high  power  that  will  run  with 
p^minmiji^vibr.atioil  and  that  produces  smooth  action.  This 
is  well  shcnvii  by  diagrams  at  Fig.  31.  It  should  be  re- 
membered that  if  an  eight-cylinder  engine  will  give  four 
explosions  per  revolution  of  the  fly-wheel,  a  twelve-cylinder 
type  will  give  six  explosions  per  revolution,  and  instead 
of  the  impulses  coming  90  degrees  crank  travel  apart,  as 
in  the  case  of  the  eight-cylinder,  these  will  come  but  60 


Overhead  Cam  Shaft 


•Magneto, 


Water 
Pump 


Oil  Sump 


Engine  Base 


Fig.  35. — The  Hall-Scott  Six-Cylinder  Aviation  Engine. 

degrees  of  crank  travel  apart  in  the  case  of  the  twelve- 
cylinder.  For  this  reason,  the  cylinders  of  a  twelve  are 
usually  separated  by  60  degrees  while  the  eight  has  the 
blocks  spaced  90  degrees  apart.  The  comparison  can  be 
easily  made  hy  comparing  the  sectional  views  of  Vee 
engines  at  Fig.  32.  When  one  realizes  that  the  actual 
duration  of  the  power  stroke  is  considerably  greater  than 
120  degrees  crank  travel,  it  will  be  apparent  that  the 
overlapping  of  explosions  must  deliver  a  very  uniform 
application  of  power.  Vee  engines  have  been  devised 


Radial  Cylinder  Arrangements 


103 


having  the  cylinders  spaced  but  45  degrees  apart,  but  the 
explosions  cannot  be  timed  at  equal  intervals  as  when  90 
degrees  separate  the  cylinder  center  lines. 

RADIAL,    CYLINDER   ARRANGEMENTS 

While  the  fixed  cylinder  forms  of  engines,  having  the 
cylinders  in  tandem  in  the  four-  and  six-cylinder  models 
as  shown  at  Figs.  33  to  35  inclusive  and  the  eight-cylinder 
V  types  as  outlined  at  Figs.  36  and  37  have  been  generally 
used  and  are  most  in  favor  at  the  present  time,  other  forms 
of  motors  having  unconventional  cylinder  arrangements 
have  been  devised,  though  most  of  these  are  practically 


View  of  Power  Delivery  En; 


Fig.  36. — The  Curtiss  Eight-Cylinder,  200.  Horse-Power  Aviation  Engine. 


104  Aviation  Engines 

obsolete.  While  many  methods  of  decreasing  weight  and 
increasing  mechanical  efficiency  of  a  motor  are  known  to 
designers,  one  of  the  first  to  be  applied  to  the  construction 
of  aeronautical  power  plants  was  an  endeavor  to  group 
the  components,  which  in  themselves  were  not  extremely 
light,  into  a  form  that  would  be  considerably  lighter  than 
the  conventional  design.  As  an  example,  we  may  consider 
those  multiple-cylinder  forms  in  which  the  cylinders  are 


A 


Valve  Rockers  Intake  Pipes 

/ 
A  An          **.  *    A   A  .// 


Reduction 
Gear  Case 


Propeller 
Flange 


Carburetor 


Fig.  37. — The  Sturtevant  Eight- Cylinder,  High  Speed  Aviation  Motor. 

disposed  around  a  short  crank-case,  either  radiating  from 
a  common  center  as  at  Fig.  38  or  of  the  fan  shape  shown 
*at  Fig.  39.  This  makes  it  possible  to  use  a  crank-case  but 
slightly  larger  than  that  needed  for  one  or  two  cylinders 
and  it  also  permits  of  a  corresponding  decrease  in  length 
of  the  crank-shaft.  The  weight  of  the  engine  is  lessened 
because  of  the  reduction  in  crank-shaft  and  crank-case 
weight  and  the  elimination  of  a  number  of  intermediate 
bearings  and  their  supporting  webs  which  would  be  neces- 
sary with  the  usual  tandem  construction.  While  there  are 
six  power  impulses  to  every  two  revolutions  of  the  crank- 


Radial  Cylinder  Arrangements 


105 


shaft,  in  the  six-cylinder  engine,  they  are  not  evenly  spaced 
as  is  possible  with  the  conventional  arrangement. 

In  the  Anzani  form,  which  is  shown  at  Fig.  38,  the  crank- 
case  is  stationary  and  a  revolving  crank-shaft  is  employed 
as  in  conventional  construction.  The  cylinders  are  five 


Fig.  38. — Anzani  40-50  Horse-Power  Five-Cylinder  Air  Cooled  Engine. 

in  number  and  the  engine  develops  40  to  50  H.  P.  with  a 
weight  of  72  kilograms  or  158.4  Ibs.  The  cylinders  are  of 
the  usual  air-cooled  form  having  cooling  flanges  only  part 
of  the  way  down  the  cylinder.  By  using  five  cylinders  it 
is  possible  to  have  the  power  impulses  come  regularly, 
they  coming  145°  crank-shaft  travel  apart,  the  crank-shaft 
making  two  turns  to  every  five  explosions.  The  balance 
is  good  and  power  output  regular.  The  valves  are 


106 


Aviation  Engines 


placed  directly  in  the  cylinder  head  and  are  operated  by 
a  common  pushrod.  Attention  is  directed  to  the  novel 
method  of  installing  the  carburetor  which  supplies  the  mix- 
ture to  the  engine  base  from  which  inlet  pipes  radiate  to 
the  various  cylinders.  This  engine  is  used  on  French 
school  machines. 

In  the  form  shown  at  Fig.  39  six  cylinders  are  used, 
all  being  placed  above  the  crank-shaft  center  line.     This 


Fig.  39. — Unconventional  Six-Cylinder  Aircraft  Motor  of  Masson  Design. 

engine  is  also  of  the  air-cooled  form  and  develops  50  H.  P. 
and  weighs  105  kilograms,  or  231  Ibs.  The  carburetor  is 
connected  to  a  manifold  casting  attached  to  the  engine  base 
from  which  the  induction  pipes  radiate  to  the  various 
cylinders.  The  propeller  design  and  size  relative  to  the 
engine  is  clearly  shown  in  this  view.  While  flights  have 
been  made  with  both  of  the  engines  described,  this  method 
of  construction  is  not  generally  followed  and  has  been 
almost  entirely  displaced  abroad  by  the  revolving  motors 
or  by  the  more  conventional  eight-cylinder  V  engines. 
Both  of  the  engines  shown  were  designed  about  eight  years 


Rotary  Cylinder  Engines  107 

ago  and  would  be  entirely  too  small  and  weak  for  use  in 
modern  airplanes  intended  for  active  duty. 


ROTARY    ENGINES 


Rotary  engines  such  as  shown  at  Fig.  40  are  generally 
associated  with  the  idea  of  light  construction  and  it  is 


Fig.  40. — The  Gnome  Fourteen-Cylinder  Revolving  Motor. 

rather  an  interesting  point  that  is  often  overlooked  in 
connection  with  the  application  of  this  idea  to  flight 
motors,  that  the  reason  why  rotary  engines  are  popularly 
supposed  to  be  lighter  than  the  others  is  because  they  form 
their  own  fly-wheel,  yet  on  aeroplanes,  engines  are  seldom 
fitted  with  a  fly-wheel  at  all.  As  a  matter  of  fact  the 


108  Aviation  Engines 

Gnome  engine  is  not  so  light  because  it  is  a  rotary  motor, 
and  it  is  a  rotary  motor  because  the  design  that  has 
been  adopted  as  that  most  conducive  to  lightness  is 
also  most  suited  to  an  engine  working  in  this  way. 
The  cylinders  could  be  fixed  and  crank-shaft  revolve 
without  increasing  the  weight  to  any  extent.  There 
are  two  prime  factors  governing  the  lightness  of  an 
engine,  one  being  the  initial  design,  and  the  other  the 
quality  of  the  materials  employed.  The  consideration 
of  reducing  weight  by  cutting  away  metal  is  a  subsidi- 
ary method  that  ought  not  to  play  a  part  in  standard 
practice,  however  useful  it  may  be  in  special  cases.  In 
the  Gnome  rotary  engine  the  lightness  is  entirely  due  to 
the  initial  design  and  to  the  materials  employed  in  manu- 
facture. Thus,  in  the  first  case,  the  engine  is  a  radial 
engine,  and  has  its  seven  or  nine  cylinders  spaced  equally 
around  a  crank-chamber  that  is  no  wider  or  rather  longer 
than  would  be  required  for  any  one  of  the  cylinders. 
This  shortening  of  the  crank-chamber  not  only  effects 
a  considerable  saving  of  weight  on  its  own  account,  but 
there  is  a  corresponding  saving  in  the  shafts  and  other 
members,  the  dimensions  of  which  are  governed  by  the 
size  of  the  crank-chamber.  With  regard  to  materials, 
nothing  but  steel  is  used  throughout,  and  most  of  the  metal 
is  forged  chrome  nickel  steel.  The  beautifully  steady 
running  of  the  engine  is  largely  due  to  the  fact  that  there 
are  literally  no  reciprocating  parts  in  the  absolute  sense, 
the  apparent  reciprocation  between  the  pistons  and  cylin- 
ders being  solely  a  relative  reciprocation  since  both  travel 
in  circular  paths,  that  of  the  pistons,  however,  being 
ele'ctric  by  one-half  of  the  stroke  length  to  that  of  the 
cylinder. 

While  the  Gnome  engine  has  many  advantages,  on  the 
other  hand  the  head  resistance  offered  by  a  motor  of  this 
type  is  considerable;  there  is  a  large  waste  of  lubricating 
oil  due  to  the  centrifugal  force  which  tends  to  throw  the 
oil  away  from  the  cylinders;  the  gyroscopic  effect  of  the 
rotary  motor  is  detrimental  to  the  best  working  of  the 


Rotary  Cylinder  Engines  109 

aeroplane,  and  moreover  it  requires  about  seven  per  cent, 
of  the  total  power  developed  by  the  motor  to  drive  the 
revolving  cylinders  around  the  shaft.  Of  necessity,  the 
compression  of  this  type  of  motor  is  rather  low,  and  an 
additional  disadvantage  manifests  itself  in  the  fact  that 
there  is  as  yet  no  satisfactory  way  of  muffling  the  rotary 
type  of  motor.  The  modern  Gnome  engine  has  been  widely 
copied  in  various  European  countries,  but  its  design  was 
originated  in  America,  the  early  Adams-Farwell  engine 
being  the  pioneer  form.  It  has  been  made  in  seven-  and 
nine-cylinder  types  and  forms  of  double  these  numbers. 
The  engine  illustrated  at  Fig.  40  is  a  fourteen-cylinder 
form.  The  simple  engines  have  an  odd  number  of  cylin- 
ders in  order  to  secure  evenly  spaced  explosions.  In  the 
seven-cylinder,  the  impulses  come  102.8°  apart.  In  the 
nine-cylinder  form,  the  power  strokes  are  spaced  80°  apart. 
The  fourteen-cylinder  engine  is  virtually  two  seven-cylin- 
der types  mounted  together,  the  cranks  being  just  the 
same  as  in  a  double  cylinder  opposed  motor,  the  explosions 
coming  51.4°  apart;  while  in  the  eighteen-cylinder  model 
the  power  impulses  come  every  40°  cylinder  travel.  Other 
rotary  motors  have  been-  devised,  such  as  the  Le  Ehone 
and  the  Clerget  in  France  and  several  German  copies  of 
these  various  types.  The  mechanical  features  of  these 
motors  will  be  fully  considered  later. 


CHAPTER   V 

Properties  of  Liquid  Fuels — Distillates  of  Crude  Petroleum — Principles 
of  Carburetion  Outlined — Air  Needed  to  Bui»n  Gasoline — What 
a  Carburetor  Should  Do— Liquid  Fuel  Storage  and  Supply — 
Vacuum  Fuel  Feed — Early  Vaporizer  Forms — Development  of 
Float  Feed  Carburetor — Maybach's  Early  Design — Concentric 
Float  and  Jet  Type — Schebler  Carburetor — Claudel  Carburetor — 
Stewart  Metering  Pin  Type — Multiple  Nozzle  Vaporizers — Two- 
Stage  Carburetor — Master  Multiple  Jet  Type — Compound  Nozzle 
Zenith  Carburetor — Utility  of  Gasoline  Strainers — Intake  Manifold 
Design  and  Construction — Compensating  for  Various  Atmospheric 
Conditions — How  High  Altitude  Affects  Power — The  Diesel  Sys- 
tem— Notes  on  Carburetor  Installation — Notes  on  Carburetor  Ad- 
justment. 

THERE  is  no  appliance  that  has  more  material  value 
upon  the  efficiency  of  the  internal  combustion  motor  than 
the  carburetor  or  vaporizer  which  supplies  the  explosive 
gas  to  the  cylinders.  It  is  only  in  recent  years  that  en- 
gineers have  realized  the  importance  of  using  carburetors 
that  are  efficient  and  that  are  so  strongly  and  simply  made 
that  there  will  be  little  liability  of  derangement.  As  the 
power  obtained  from  the  gas-engine  depends  upon  the 
combustion  of  fuel  in  the  cylinders,  it  is  evident  that  if 
the  gas  supplied  does  not  have  the  proper  proportions  of 
elements  to  insure  rapid  combustion  the  efficiency  of  the 
engine  will  be  low.  When  a  gas  engine  is  used  as  a  sta- 
tionary installation  it  is  possible  to  use  ordinary  illuminat- 
ing or  natural  gas  for  fuel,  but  when  this  prime  mover  is 
applied  to  automobiles  or  airplanes  it  is  evident  that  con- 
siderable difficulty  would  be  experienced  in  carrying  enough 
compressed  coal  gas  to  supply  the  engine  for  even  a  very 
short  trip.  Eortunately,  the  development  of  the  internal- 
combustion  motor  was  not  delayed  by  the  lack  of  suitable 
fuel. 

Engineers  \tere  familiar  with  the  properties  of  certain 

no 


Distillates  of  Crude  Petroleum  111 

liquids  which  gave  off  vapors  that  could  be  mixed  with  air 
to  form  an  explosive  gas  which  burned  very  well  in  the 
engine  cylinders.  A  very  small  quantity  of  such  liquids 
would  suffice  for  a  very  satisfactory  period  of  operation. 
The  problem  to  be  solved  before  these  liquids  could  be 
applied  in  a  practical  manner  was  to  evolve  suitable  ap- 
paratus for  vaporizing  them  without  waste.  Among  the 
liquids  that  can  be  combined  with  air  and  burned,  gasoline 
is  the  most  volatile  and  is  the  fuel  utilized  by  internal- 
combustion  engines. 

The  widely  increasing  scope  of  usefulness  of  the  in- 
ternal-combustion motor  has  made  it  imperative  that  other 
fuels  be  applied  in  some  instances  because  the  supply  of 
gasoline  may  in  time  become  inadequate  to  supply  the 
demand.  In  fact,  abroad  this  fuel  sells  for  fifty  to  two* 
hundred  per  cent,  more  than  it  does  in  America  because 
most  of  the  gasoline  used  must  be  imported  from  this 
country  or  Russia.  Because  of  this  foreign  engineers  have 
experimented  widely  with  other  substances,  such  as  alco- 
hol, benzol,  and  kerosene,  but  more  to  determine  if  they 
can  be  used  to  advantage  in  motor  cars  than  in  airplane 
engines. 

DISTILLATES   OF    CRUDE   PETROLEUM 

Crude  petroleum  is  found  in  small  quantities  in  almost 
all  parts  of  the  world,  but  a  large  portion  of  that  pro- 
duced commercially  is  derived  from  American  wells.  The 
petroleum  obtained  in  this  country  yields  more  of  the 
volatile  products  than  those  of  foreign  production,  and  for 
that  reason  the  demand  for  it  is  greater.  The  oil  fields 
of  this  country  are  found  in  Pennsylvania,  Indiana,  and 
Ohio,  and  the  crude  petroleum  is  usually  in  association 
with  natural  gas.  This  mineral  oil  is  an  agent  from  which 
many  compounds  and  products  are  derived,  and  the  prod- 
ucts will  vary  from  heavy  sludges,  such  as  asphalt,  to 
the  lighter  and  more  volatile  components,  some  of  which 
will  evaporate  very  easily  at  ordinary  temperatures. 

The  compounds  derived  from  crude  petroleum  are  com- 


112  Aviation  Engines 

posed  principally  of  hydrogen  and  carbon  and  are  termed 
"Hydrocarbons."  In  the  crude  product  one  finds  many 
impurities,  such  as  free  carbon,  sulphur,  and  various 
earthy  elements.  Before  the  oil  can  be  utilized  it  must  be 
subjected  to  a  process  of  purifying  which  is  known  as 
refining,  and  it  is  during  this  process,  which  is  one  of 
•destructive  distillation,  that  the  various  liquids  are  sepa- 
rated. The  oil  was  formerly  broken  up  into  three  main 
.groups  of  products  as  follows :  Highly  volatile,  naphtha, 
benzine,  gasoline,  eight  to  ten  per  cent.  Light  oils,  such 
as  kerosene  and  light  lubricating  oils  seventy  to  eighty 
per  cent.  Heavy  oils  or  residuum  five  to  nine  per  cent. 
From  the  foregoing  it  will  be  seen  that  the  available  sup- 
ply of  gasoline  is  determined  largely  by  the  demand  exist- 
ing for  the  light  oils  forming  the  larger  part  of  the 
products  derived  from  crude  petroleum.  New  processes 
have  been  recently  discovered  by  which  the  lighter  oils, 
such  as  kerosene,  are  reduced  in  proportion  and  that  of 
gasoline  increased,  though  the  resulting  liquid  is  neither 
the  high  grade,  volatile  gasoline  known  in  the  early  days 
of  motoring  nor  the  low  grade  kerosene. 

PRINCIPLES    OF    CARBURETION    OUTLINED 

The  process  of  carburetion  is  combining  the  volatile 
vapors  which  evaporate  from  the  hydrocarbon  liquids  with 
certain  proportions  of  air  to  form  an  inflammable  gas. 
The  quantities  of  air  needed  vary  with  different  liquids 
and  some  mixtures  burn  quicker  than  do  other  combina- 
tions of  air  and  vapor.  Combustion  is  simply  burning  and 
it  may  be  rapid,  moderate  or  slow.  Mixtures  of  gasoline 
and  air  burn  quickly,  in  fact  the  combustion  is  so  rapid 
that  it  is  almost  instantaneous  and  we  obtain  what  is 
commonly  termed  an  "explosion."  Therefore  the  ex- 
plosion of  gas  in  the  automobile  engine  cylinder  which 
produces  the  power  is  really  a  combination  of  chemical 
elements  which  produce  heat  and  an  increase  in  the  vol- 
ume of  the  gas  because  of  the  increase  in  temperature. 

If  the  gasoline  mixture  is  not  properly  proportioned 


Air  Needed  to  Burn  Gasoline  113 

the  rate  of  burning  will  vary,  and  if  the  mixture  is  either 
too  rich  or  too  weak  the  power  of  the  explosion  is  reduced 
and  the  amount  of  power  applied  to  the  piston  is  de- 
creased proportionately.  In  determining  the  proper  pro- 
portions of  gasoline  and  air,  one  must  take  the  chemical 
composition  of  gasoline  into  account.  The  ordinary  liquid 
used  for  fuel  is  said  to  contain  about  eight-four  per  cent, 
carbon  and  sixteen  per  cent,  hydrogen.  Air  is  composed 
of  oxygen  and  nitrogen  and  the  former  has  a  great  affinity, 
or  combining  power,  with  the  two  constituents  of  hydro- 
carbon liquids.  Therefore,  what  we  call  an  explosion  is 
merely  an  indication  that  oxygen  in  the  air  has  combined 
with  the  carbon  and  hydrogen  of  the  gasoline. 

AIR  NEEDED  TO  BURN  GASOLINE 

In  figuring  the  proper  volume  of  air  to  mix  with  a 
given  quantity  of  fuel,  one  takes  into  account  the  fact  that 
one  pound  of  hydrogen  requires  eight  pounds  of  oxygen 
to  burn  it,  and  one  pound  of  carbon  needs  two  and  one- 
third  pounds  of  oxygen  to  insure  its  combustion.  Air  is 
composed  of  one  part  of  oxygen  to  three  and  one-half  por- 
tions of  nitrogen  by  weight.  Therefore  for  each  pound  of 
oxygen  one  needs  to  burn  hydrogen  or  carbon  four  and 
one-half  pounds  of  air  must  be  allowed.  To  insure  com- 
bustion of  one  pound  of  gasoline  which  is  composed  of 
hydrogen  and  carbon  we  must  furnish  about  ten  pounds 
of  air  to  burn  the  carbon  and  about  six  pounds  of  air  to 
insure  combustion  of  hydrogen,  the  other  component  of 
gasoline.  This  means  that  to  burn  one  pound  of  gasoline 
one  must  provide  about  sixteen  pounds  of  air. 

While  one  does  not  usually  consider  air  as  having  much 
weight,  at  a  temperature  of  sixty-two  degrees  Fahrenheit 
about  fourteen  cubic  feet  of  air  will  weigh  a  pound,  and 
to  burn  a  pound  of  gasoline  one  would  require  about  two 
hundred  cubic  feet  of  air.  This  amount  will  provide  for 
combustion  theoretically,  but  it  is  common  practice  to 
allow  twice  this  amount  because  the  element  nitrogen, 
which  is  the  main  constituent  of  air,  is  an  inert  gas  and 


114  Aviation  Engines 

« 
instead  of  aiding  combustion  it  acts  as  a  deterrent  of 

burning.  In  order  to  be  explosive,  gasoline  vapor  must 
be  combined  with  definite  quantities  of  air.  Mixtures  that 
are  rich  in  gasoline  ignite  quicker  than  those  which  have 
more  air,  but  these  are  only  suitable  when  starting  or 
when  running  slowly,  as  a  rich  mixture  ignites  much 
quicker  than  a  weak  mixture.  The  richer  mixture  of 
gasoline  and  air  not  only  burns  quicker  but  produces  the 
most  heat  and  the  most  effective  pressure  in  pounds  per 
square  inch  of  piston  top  area. 

The  amount  of  compression  of  the  charge  before  igni- 
tion also  has  material  bearing  on  the  force  of  the  explo- 
sion. The  higher  the  degree  of  compression  the  greater 
the  force  exerted  by  the  rapid  combustion  of  the  gas.  It 
may  be  stated  that  as  a  general  thing  the  maximum  ex- 
plosive pressure  is  somewhat  more  than  four  times  the 
compression  pressure  prior  to  ignition.  A  charge  com- 
pressed to  sixty  pounds  will  have  a  maximum  of  approxi- 
mately two  hundred  and  forty  pounds;  compacted  to 
eighty  pounds  it  will  produce  a  pressure  of  about  three 
hundred  pounds  on  each  square  inch  of  piston  area  at 
the  beginning  of  the  power  stroke.  Mixtures  varying 
from  one  part  of  gasoline  vapor  to  four  of  air  to  others 
having  one  part  of  gasoline  vapor  to  thirteen  of  air  can 
be  ignited,  but  the  best  results  are  obtained  when  the 
proportions  are  one  to  five  or  one  to  seven,  as  this  mix- 
ture is  said  to  be  the  one  that  will  produce  the  high- 
est temperature,  the  quickest  explosion,  and  the  most 
pressure. 

WHAT  A   CAEBUKETOR   SHOULD  DO 

While  it  is  apparent  that  the  chief  function  of  a  car- 
bureting device  is  to  mix  hydrocarbon  vapors  with  air  to 
secure  mixtures  that  will  burn,  there  are  a  number  of  fac- 
tors which  must  be  considered  before  describing  the  prin- 
ciples of  vaporizing  devices.  Almost  any  device  which 
permits  a  current  of  air  to  pass  over  or  through  a  vola- 
tile liquid  will  produce  a  gas  which  will  explode  when 


What  a  Carburetor  Should  Do 


115 


11 


I? 

I 

o 


116  Aviation  Engines 

compressed  and  ignited  in  the  motor  cylinder.  Modern 
carburetors  are  not  only  called  upon  to  supply  certain 
quantities  of  gas,  but  these  must  deliver  a  mixture  to  the 
cylinders  that  is  accurately  proportioned  and  which  will 
be  of  proper  composition  at  all  engine  speeds. 

Flexible  control  of  the  engine  is  sought  by  varying  the 
engine  speed  by  regulating  the  supply  of  gas  to  the  cylin- 
ders. The  power  plant  should  run  from  its  lowest  to  its 
highest  speed  without  any  irregularity  in  torque,  i.e.,  the 
acceleration  should  be  gradual  rather  than  spasmodic.  As 
the  degree  of  compression  will  vary  in  value  with  the 
amount  of  throttle  opening,  the  conditions  necessary  to 
obtain  maximum  power  differ  with  varying  engine  speeds. 
When  the  throttle  is  barely  opened  the  engine  speed  is 
low  and  the  gas  must  be  richer  in  fuel  than  when  the 
throttle  is  wide  open  and  the  engine  speed  high. 

"When  an  engine  is  turning  over  slowly  the  compression 
has  low  value  and  the  conditions  are  not  so  favorable  to 
rapid  combustion  as  when  the  compression  is  high.  At 
high  engine  speeds  the  gas  velocity  through  the  intake 
piping  is  higher  than  at  low  speeds, 'and  regular  engine 
action  is  not  so  apt  to  be  disturbed  by  condensation  of 
liquid  fuel  in  the  manifold  due  to  excessively  rich  mixture 
or  a  superabundance  of  liquid  in  the  stream  of  carbureted 
air. 

LIQUID  FUEL,  STORAGE  AND  SUPPLY 

The  problem  of  gasoline  storage  and  method  of  supply- 
ing the  carburetor  is  one  that  is  determined  solely  by 
design  of  the  airplane.  While  the  object  of  designers 
should  be  to  supply  the  fuel  to  the  carburetor  by  as  'simple 
means  as  possible  the  fuel  supply  system  of  some  airplanes 
is  quite  complex.  The  first  point  to  consider  is  the  loca- 
tion of  the  gasoline  tank.  This  depends  upon  the  amount 
of  fuel  needed  and  the  space  available  in  the  fuselage. 

A  very  simple  and  compact  fuel  supply  system  is  shown 
at  Fig.  41.  In  this  instance  the  fuel  container  is  placed 
immediately  back  of  the  engine  cylinder.  The  carburetor 


Liquid  Fuel  Storage  and  Supply  117 

which  is  carried  as  indicated  is  joined  to  the  tank  by  a 
short  piece  of  copper  or  flexible  rubber  tubing.  This  is 
the  simplest  possible  form  of  fuel  supply  system  and  one 
used  on  a  number  of  excellent  airplanes. 

As  the  sizes  of  engines  increase  and  the  power  plant 
fuel  consumption  augments  it  is  necessary  to  use  more 
fuel,  and  to  obtain  a  satisfactory  flying  radius  without 
frequent  landings  for  filling  the  fuel  tank  it  is  necessary 
to  supply  large  containers. 

When  a  very  powerful  power  plant  is  fitted,  as  on 
battle  planes  of  high  capacity,  it  is  necessary  to  carry 
large  quantities  of  gasoline.  In  order  to  use  a  tank  of 
sufficiently  large  capacity  it  may  be  necessary  to  carry  it 
lower  than  the  carburetor.  When  installed  in  this  manner 
it  is  necessary  to  force  fuel  out  of  the  tank  by  air  pres- 
sure or  to  pump  it  with  a  vacuum  tank  because  the  gasoline 
tank  is  lower  than  the  carburetor  it  supplies  and  the  gaso- 
line cannot  flow  by  gravity  as  in  the  simpler  systems. 
While  the  pressure  and  gravity  feed  systems  are  generally 
used  in  airplanes,  it  may  be  well  to  describe  the  vacuum 
lift  system  which  has  been  widely  applied  to  motor  cars 
and  which  may  have  some  use  in  connection  with  airplanes 
as  these  machines  are  developed. 

STEWART  VACUUM  FUEL  FEED 

One  of  the  marked  tendencies  has  been  the  adoption 
of  a  vacuum  fuel  feed  system  to  draw  the  gasoline  from 
tanks  placed  lower  than  the  carburetor  instead  of  using 
either  exhaust  gas  or  air  pressure  to  achieve  this  end.  The 
device  generally  fitted  is  the  Stewart  vacuum  feed  tank 
which  is  clearly  shown  in  section  at  Fig.  42.  In  this  sys- 
tem the  suction  of  a  motor  is  employed  to  draw  gasoline 
from  the  main  fuel  tank  to  the  auxiliary  tank  incorporated 
in  the  device  and  from  this  tank  the  liquid  flows  to  the 
carburetor.  It  is  claimed  that  all  the  advantages  of  the 
pressure  system  are  obtained  with  very  little  more  com- 
plication than  is  found  on  the  ordinary  gravity  feed.  The 
mechanism  is  all  contained  in  the  cylindrical  tank  shown, 


118 


Aviation  Engines 


which  may  be  mounted  either  on  the  front  of  the  dash  or 
on  the  side  of  the  engine  as  shown. 

The  tank  is  divided  into  two  chambers,  the  upper  one 
being  the  filling  chamber  and  the  lower  one  the  emptying 


Atmospheric  Valve 
Suction  Valve  ^ 
,'Fr0m  Gasoline  Tank 


'Suction  Pipe 


Fig.  42.— The  Stewart  Vacuum  Fuel  Feed  Tank. 

chamber.  The  former,  which  is  at  the  top  of  the  device, 
contains  the  float  valve,  as  well  as  the  pipes  running  to 
the  main  fuel  container  and  to  the  intake  manifold.  The 
lower  chamber  is  used  to  supply  the  carburetor  with  gaso- 
line and  is  under  atmospheric  pressure  at  all  times,  so  the 
flow  of  fuel  from  it  is  by  means  of  gravity  only.  Since 


Stewart  Vacuum  Feed  System  119 

this  chamber  is  located  somewhat  above  the  carburetor, 
there  must  always  be  free  flow  of  fuel.  Atmospheric  pres- 
sure is  maintained  by  the  pipes  A  and  B,  the  latter  open- 
ing into  the  air.  In  order  that  the  fuel  will  be  sucked 
from  a  main  tank  to  the  upper  chamber,  the  suction  valve 
must  be  opened  and  the  atmospheric  valve  closed.  Under 
these  conditions  the  float  is  at  the  bottom  and  the  suction 
at  the  intake  manifold  produces  a  vacuum  in  the  tank 
which  draws  the  gasoline  from  the  main  tank  to  the  upper 
chamber.  When  the  upper  chamber  is  filled  at  the  proper 
height  the  float  rises  to  the  top,  this  closing  the  suction 
valve  and  opening  the  atmospheric  valve.  As  the  suction 
is  now  cut  off,  the  lower  chamber  is  filled  by  gravity  owing 
to  there  being  atmospheric  pressure  in  both  upper  and 
lower  chambers.  A  flap  valve  is  provided  between  the 
two  chambers  to  prevent  the  gasoline  in  the  lower  one 
from  being  sucked  back  into  the  upper  one.  The  atmos- 
pheric and  suction  valves  are  controlled  by  the  levers  C 
and  D,  both  of  which  are  pivoted  at  E,  their  outer  ends 
being  connected  by  two  coil  springs.  It  is  seen  that  the 
arrangement  of  these  two  springs  is  such  that  the  float 
must  be  held  at  the  extremity  of  its  movement,  and  that 
it  cannot  assume  an  intermediate  position. 

This  intermittent  action  is  required  to  insure  that  the 
upper  part  of  the  tank  may  be  under  atmospheric  pressure 
part  of  the  time  for  the  gasoline  to  flow  to  the  lower  cham- 
ber. When  the  level  of  gasoline  drops  to  a  certain  point, 
the  float  falls,  thus/  opening  the  suction  valve  and  closing 
the  atmospheric  valve.  The  suction  of  the  motor  then 
causes  a  flow  of  fuel  from  the  main  container.  As  soon 
as  the  level  rises  to  the  proper  height  the  float  returns  to 
its  upper  position.  It  takes  about  two  seconds  for  the 
chamber  to  become  full  enough  to  raise  the  float,  as  but 
.05  gallon  is  transferred  at  a  time.  The  pipe  running  from 
the  bottom  of  the  lower  chamber  to  the  carburetor  extends 
up  a  ways,  so  that  there  is  but  little  chance  of  dirt  or  water 
being  carried  to  the  float  chamber. 

If  the  engine  is  allowed  to  stand  long  enough  so  that  the 


120  Aviation  Engines 

tank  becomes  empty,  it  will  be  replenished  after  the  motor 
has  been  cranked  over  four  or  five  times  with  the  throttle 
closed.  The  installation  of  the  Stewart  Vacuum- Gravity 
System  is  very  simple.  The  suction  pipe  is  tapped  into 
the  manifold  at  a  point  as  near,  the  cylinders  as  possible, 
while  the  fuel  pipe  is  inserted  into  the  gasoline  tank  and 
runs  to  the  bottom  of  that  member.  There  is  a  screen  at 
the  end  of  the  fuel  pipe  to  prevent  any  trouble  due  to  de- 
posits of  sediment  in  the  main  container.  As  the  fuel  is 
sucked  from  the  gasoline  tank  a  small  vent  must  be  made 
in  the  tank  filler  cap  so  that  the  pressure  in  the  main  tank 
will  always  be  that  of  the  atmosphere. 

EARLY    VAPORIZER    FORMS 

The  early  types  of  carbureting  devices  were  very  crude 
and  cumbersome,  and  the  mixture  of  gasoline  vapor  and 
air  was  accomplished  in  three  ways.  The  air  stream  was 
passed  over  the  surface  of  the  liquid  itself,  through  loosely 
placed  absorbent  material  saturated  with  liquid,  or  directly 
through  the  fuel.  The  first  type  is  known  as  the  surface 
carburetor  and  is  now  practically  obsolete.  The  second 
form  is  called  the  "wick"  carburetor  because  the  air 
stream  was  passed  over  or  through  saturated  wicking.  The 
third  form  was  known  as  a  "bubbling"  carburetor.  While 
these  primitive  forms  gave  fairly  good  results  with  the 
early  slow-speed  engines  and  the  high  grade,  or  very 
volatile,  gasoline  which  was  first  used  for  fuel,  they  would 
be  entirely  unsuitable  for  present  forms  of  engines  be- 
cause they  would  not  carburate  the  lower  grades  of  gaso- 
line which  are  used  to-day,  and  would  not  supply  the 
modern  high-speed  engines  with  gas  of  the  proper  consis- 
tency fast  enough  even  if  they  did  not  have  to  use  very 
volatile  gasoline.  The  form  of  carburetor  used  at  the 
present  time  operates  on  a  different  principle.  These 
devices  are  known  as  "spraying  carburetors."  The  fuel 
is  reduced  to  a  spray  by  the  suction  effect  of  the  entering 
air  stream  drawing  it  through  a  fine  opening. 

The   advantage   of   this   construction   is   that   a   more 


Early  Vaporizer  Form* 


121 


thorough  amalgamation  of  the  gasoline  and  air  particles 
is  obtained.  With  the  earlier  types  previously  considered 
the  air  would  combine  with  only  the  more  volatile  elements, 
leaving  the  heavier  constituents  in  the  tank.  As  the  fuel 
became  stale  it  was  difficult  to  vaporize  it,  and  it  had  to 


Jump  Value 
Adjustment 


Mixture 
Passage 


Gasoline  Adjustment 


Fig.  43. — Marine-Type  Mixing  Valve,  by  which  Gasoline  is  Sprayed  into  Air 
Stream  Through  Small  Opening  in  Air-Valve  Seat. 

be  drained  off  and  fresh  fuel  provided  before  the  proper 
mixture  would  be  produced.  It  will  be  evident  that  when 
the  fuel  is  sprayed  into  the  air  stream,  all  the  fuel  will  be 
used  up  and  the  heavier  portions  of  the  gasoline  will  be 
taken  into  the  cylinder  and  vaporized  just  as  well  as  the 
more  volatile  vapors. 

The  simplest  form  of  spray  carburetor  is  that  shown 
at  Fig.  43.     In  this  the  gasoline  opening  through  which 


122  Aviation  Engines 

the  fuel  is  sprayed  into  the  entering  air  stream  is  closed 
by  the  spring-controlled  mushroom  valve  which  regulates 
the  main  air  opening  as  well.  When  the  engine  draws  in 
a  charge  of  air  it  unseats  the  valve  and  at  the  same  time 
the  air  flowing  around  it  is  saturated  with  gasoline  par- 
ticles through  the  gasoline  opening.  The  mixture  thus 
formed  goes  to  the  engine  through  the  mixture  passage, 
Two  methods  of  varying  the  fuel  proportions  are  provided. 
One  of  these  consists  of  a  needle  valve  to  regulate  the 
amount  of  gasoline,  the  other  is  a  knurled  screw  which 
controls  the  amount  of  air  by  limiting  the  lift  of  the 
jump  valve. 

DEVELOPMENT   OF   FLOAT-FEED    CARBURETOR 

The  modern  form  of  spraying  carburetor  is  provided 
with  two  chambers,  one  a  mixing  chamber  through  which 
the  air  stream  passes  and  mixes  with  a  gasoline  spray, 
the  other  a  float  chamber  in  which  a  constant  level  of  fuel 
is  maintained  by  simple  mechanism.  A  jet  or  standpipe 
is  used  in  the  mixing  chamber  to  spray  the  fuel  through 
and  the  object  of  the  float  is  to  maintain  the  fuel  level 
to  such  a  point  that  it  will  not  overflow  the  jet  when  the 
motor  is  not  drawing  in  a  charge  of  gas.  With  the  simple 
forms  of  generator  valve  in  which  the  gasoline  opening  is 
controlled  by  the  air  valve,  a  leak  anywhere  in  either 
valve  or  valve  seat  will  allow  the  gasoline  to  flow  continu- 
ously whether  the  engine  is  drawing  in  a  charge  or  not. 
The  liquid  fuel  collects  around  the  air  opening,  and  when 
the  engine  inspires  a  charge  it  is  saturated  with  gasoline 
globules  and  is  excessively  rich.  With  a  float-feed  con- 
struction, which  maintains  a  constant  level  of  gasoline  at 
the  right  height  in  the  standpipe,  liquid  fuel  will  only  be 
supplied  when  drawn  out  of  the  jet  by  the  suction  effect 
of  the  entering  air  stream. 


MAYBACH'S  EARLY  DESIGN 


The  first   form  of   spraying  carburetor   ever   applied 
successfully  was  evolved  by  Maybach  for  use  on  one  of  the 


Maybaclis  Early  Design 


123 


124  Aviation  Engines 

earliest  Daimler  engines.  The  general  principles  of  opera- 
tion of  this  pioneer  float-feed  carburetor  are  shown  at 
Fig.  44,  A.  The  mixing  chamber  and  valve  chamber  were 
one  and  the  standpipe  or  jet  protruded  into  the  mixing 
chamber.  It  was  connected  to  the  float  compartment  by  a 
pipe.  The  fuel  from  the  tank  entered  the  top  of  the  float 
compartment  and  the  opening  was  closed  by  a  needle 
valve  carried  on  top  of  a  hollow  metal  float.  When  the 
level  of  gasoline  in  the  float  chamber  was  lowered  the 
float  would  fall  and  the  needle  valve  uncover  the  opening. 
This  would  permit  the  gasoline  from  the  tank  to  flow  into 
the  float  chamber,  and  as  the  chamber  filled  the  float  would 
rise  until  the  proper  level  had  been  reached,  under  which 
conditions  the  float  would  shut  off  the  gasoline  opening. 
On  every  suction  stroke  of  the  engine  the  inlet  valve,  which 
was  an  automatic  type,  would  leave  its  seat  and  a  stream 
of  air  would  be  drawn  through  the  air  opening  and  around 
the  standpipe  or  jet.  This  would  cause  the  gasoline  to 
spray  out  of  the  tube  and  mix  with  the  entering  air  stream. 
The  form  shown  at  B  ivas  a  modification  of  Maybach's 
simple  device  and  was  first  used  on  the  Phoenix-Daimler 
engines.  Several  improvements  are  noted  in  this  device. 
First,  the  carburetor  was  made  one  unit  by  casting  the 
float  and  mixing  chambers  together  instead  of  making  them 
separate  and  joining  them  by  a  pipe,  as  shown  at  A.  The 
float  construction  was  improved  and  the  gasoline  shut-off 
valve  was  operated  through  leverage  instead  of  being  di- 
rectly fastened  to  the  float.  The  spray  nozzle  was  sur- 
rounded by  a  choke  tube  which  concentrated  the  air  stream 
around  it  and  made  for  more  rapid  air  flow  at  low  engine 
speeds.  A  conical  piece  was  placed  over  the  jet  to  break 
up  the  entering  spray  into  a  mist  and  insure  more  intimate 
admixture  of  air  and  gasoline.  The  air  opening  was 
provided  with  an  air  cone  which  had  a  shutter  controlling 
the  opening  so  that  the  amount  of  air  entering  could  be 
regulated  and  thus  vary  the  mixture  proportions  within 
certain  limits. 


Schebler  Carburetor  Construction  125 


CONCENTRIC    FLOAT    AND    JET    TYPE 

The  form  shown  at  B  has  been  further  improved,  and 
the  type  shown  at  C  is  representative  of  modern  single 
jet  practice.  In  this  the  float  chamber  and  mixing  chamber 
are  concentric.  A  balanced  float  mechanism  which  insures 
steadiness  of  feed  is  used,  the  gasoline  jet  or  standpipe 
is  provided  with  a  needle  valve  to  vary  the  amount  of 
gasoline  supplied  the  mixture  and  two  air  openings  are 
provided.  The  main  air  port  is  at  the  bottom  of  the 
vaporizer,  while  an  auxiliary  air  inlet  is  provided  at  the 
side  of  the  mixing  chamber.  There  are  two  methods  of 
controlling  the  mixture  proportions  in  this  form  of  car- 
buretor. One  may  regulate  the  gasoline  needle  or  adjust 
the  auxiliary  air  valve. 

SCHEBLER    CARBURETOR 

A  Schebler  carburetor,  which  has  been  used  on  some 
airplane  engines,  is  shown  in  Fig.  45.  It  will  be  noticed 
that  a  metering  pin  or  needle,  valve  opens  the  jet  when 
the  air  valve  opens.  The  long  arm  of  a  leverage  is  con- 
nected to  the  air  valve,  while  the  short  arm  is  connected 
to  the  needle,  the  reduction  in  leverage  being  such  that 
the  needle  valve  is  made  to  travel  much  less  than  the  air 
valve.  For  setting  the  amount  of  fuel  passed  or  the  size 
of  the  jet  orifice  when  running  with  the  air  valve  closed, 
there  is  a  screw  which  raises  or  lowers  the  fulcrum  of 
the  lever  and  there  is  also  a  dash  control  having  the  same 
effect  by  pushing  down  the  fulcrum  against  a  small  spring. 
A  long  extension  is  given  to  the  venturi  tube  which*  is  very 
narrow  around  the  jet  orifices,  which  are  horizontal  and 
shown  at  A  in  the  drawing.  Fuel  enters  the  float  chamber 
through  the  union  M,  and  the  spring  P  holds  the  metering 
pin  upward  against  the  restraining  action  of  the  lever. 
The  air  valve  may  be  set  by  an  easily  adjustable  knurled 
screw  shown  in  the  drawing,  and  fluttering  of  the  valve  is 
prevented  by  the  piston  dash  pot  carried  in  a  chamber 
above  the  valve  into  which  the  valve  stem  projects.  The 


126 


Aviation  Engines 


Claudel  Carburetor 


127 


primary  air  enters  beneath  the  jet  passage  and  there  is 
a  small  throttle  in  the  intake  to  increase  the  speed  of  air 
flow  for  starting  purposes.  The  carburetor  is  adapted  for 
the  use  of  a  hot-air  connection  to  the  stove  around  the 
exhaust  pipe  and  it  is  recommended  that  such  a  fitting  be 
supplied.  The  lever  which  controls  the  supply  of  air 


Float  Yalve. 


,- Mixture  Outlet 


,., -Throttle 


Float 


Bowl -> 


^-Mixing 

Chamber. 


Compound 
Spray  Nozzle 


filter 

Screen' 


Fig.  46. — The  Claudel  Carburetor 

through  the  primary  air  intake  is  so  arranged  that  if 
desired  it  can  be  connected  with  a  linkage  on  the  dash 
or  control  column  by  means  of  a  flexible  wire. 

THE    CLAUDEL    (FRENCH)    CARBURETOR 

This  carburetor  is  of  extremely  simple  construction, 
because  it  has  no  supplementary  or  auxiliary  air  valve 
and  no  moving  parts  except  the  throttle  controlling  the 
gas  flow.  The  construction  is  already  shown  in  Fig.  46. 


128  Aviation  Engines 

The  spray  jet  is  eccentric  with  a  surrounding  sleeve  or 
tube  in  which  there  are  two  series  of  small  orifices,  one 
at  the  top  and  the  other  near  the  bottom.  The  former 
are  about  level  with  the  spray  jet  opening.  The  sleeve 
surrounding  the  nozzle  'is  closed  at  the  top.  The  air, 
passing  the  upper  holes  in  the  sleeve,  produces  a  vacuum 
in  the  sleeve,  thereby  drawing  air  in  through  the  bottom 
holes.  It  is  this  moving  interior  column  of  air  that  con- 
trols the  flow  of  gasoline  from  the  nozzle.  Owing  to  the 
friction  of  the  small  passages,  the  speed  of  air  flow  through 
the  sleeve  does  not  increase  as  fast  as  the  speed  of  air 
flow  outside  the  sleeve,  hence  there  is  a  tendency  for  the 
mixture  to  remain  constant.  The  throttle  of  this  carbure- 
tor is  of  the  barrel  type,  and  the  top  of  the  spray  nozzle 
and  its  surrounding  sleeve  are  located  inside  the  throttle. 

STEWART   METERING   PIN    CARBURETOR 

The  carburetor  shown  at  Fig.  47  is  a  metering  type  in 
which  the  vacuum  at  the  jet  is  controlled  by  the  weight 
of  the  metering  valve  surrounding  the  upright  metering 
pin.  The  only  moving  part  is  the  metering  valve,  which 
rises  and  falls  with  the  changes  in  vacuum.  The  air 
chamber  surrounds  the  metering  valve,  and  there  is  a  mix- 
ing chamber  above.  As  the  valve  is  drawn  up  the  gasoline 
passage  is  enlarged  on  account  of  the  predetermined  taper 
on  the  metering  pin,  and  the  air  passage  also  is  increased 
proportionately,  giving  the  correct  mixture.  A  dashpot 
at  the  bottom  of  the  valve  checks  flutter.  In  idling  the 
valve  rests  on  its  seat,  practically  closing  the  air  and  giv- 
ing the  necessary  idling  mixture.  A  passage  through  the 
valve  acts  as  an  aspirating  tube.  "When  the  valve  is  closed 
altogether  the  primary  air  passes  through  ducts  in  the 
valve  itself,  giving  the  proper  amount  for  idling.  The 
one  adjustment  consists  in  raising  or  lowering  the  tapered 
metering  pin,  increasing  or  decreasing  the  supply  of 
gasoline.  Dash  control  is  supplied.  This  pulls  down  the 
metering  pin,  increasing  the  gasoline  flow.  The  duplex 
type  for  eight-  and  twelve-cylinder  motors  is  the  same  in 


Multiple  Nozzle  Vaporizers 


129 


principle  as  model  25,  but  it  is  a  double  carburetor  syn- 
chronized as  to  throttle  movements,  adjustments,  etc.  The 
duplex  for  aeronautical  motors  is  made  of  cast  aluminum 
alloy. 

MULTIPLE   NOZZLE    VAPORIZERS 

To  secure  properly  proportioned  mixtures  some  car- 
buretor designers  have  evolved  forms  in  which  two  or 
more  nozzles  are  used  in  a  common  mixing  chamber.  The 
usual  construction  is  to  use  two,  one  having  a  small  open- 
ing and  placed  in  a  small  air  tube  and  used  only  for  low 


Th rattle  - 


Automatic 
Metering  Valve ... 


Aspirating  - 
Tube 


Dash  Pot~" 


Tapered 
Metering  Pin-—- 


Primary 
Air  Passages 


Flared  End  of 
Aspirating  Tube. 


Float 
Chamber 


Inlet  Needle  Valve 
"  -Gasoline  Strainer 


Primary 
Air  Passages 


Mixing  Chamber 


Thforf/e. 


'Automatic 
.Metering  Valve 

Automatic 
Metering  Valve 


\-AirChamber 


--  Gasoline 

Aspirant  Tube-'' 
Dash  Pot--''' 

Tapered  Tapered 

Metering  Metering  Pin- 

Pin 


,•  Primary  Air 

Passage 


^•Gasoline 
Strainer 


'Gasoline  Passage 


Fig.  47. — The  Stewart  Metering  Pin  Carburetor. 


130  Aviation  Engines 

speeds,  the  other  being  placed  in  a  larger  air  tube  and 
having  a  slightly  augmented  bore  so  that  it  is  employed 
on  intermediate  speeds.  At  high  speeds  both  jets  would 
be  used  in  series.  Some  multiple  jet  carburetors  could 
be  considered  as  a  series  of  these  instruments,  each  one 
being  designed  for  certain  conditions  of  engine  action. 
They  would  vary  from  small  size  just  sufficient  -to  run 
the  engine  at  low  speed  to  others  having  sufficient  capacity 
to  furnish  gas  for  the  highest  possible  engine  speed  when 
used  in  conjunction  with  the  smaller  members  which  have 
been  brought  into  service  progressively  as  the  engine  speed 
has  been  augmented.  The  multiple  nozzle  carburetor  dif- 
fers from  that  in  which  a  single  spray  tube  is  used  only 
in  the  construction  of  the  mixing  chamber,  as  a  common 
float  bowl  i&an  be  used  to  supply  all  spray  pipes.  It  is 
common  practice  to  bring  the  jets  into  action  progres- 
sively by  some  form  of  mechanical  connection  with  the 
throttle  or  by  automatic  valves. 

The  object  of  any  multiple  nozzle  carburetor  is  to 
secure  greater  flexibility  and  endeavor  to  supply  mix- 
tures of  proper  proportions  at  all  speeds  of  the  engine. 
It  should  be  stated,  however,  that  while  devices  of  this 
nature  lend  themselves  readily  to  practical  application  it 
is  more  difficult  to  adjust  them  than  the  simpler  forms 
having  but  one  nozzle.  When  a  number  of  jets  are  used 
the  liability  of  clogging,  up  the  carburetor  is  increased, 
and  if  one  or  more  of  the  nozzles  is  choked  by  a  particle 
of  dirt  or  water  the  resulting  mixture  trouble  is  difficult 
to  detect.  One  of  the  nozzles  may  supply  enough  gasoline 
to  permit  the  engine  to  run  well  at  certain  speeds  and  yet 
not  be  adequate  to  supply  the  proper  amount  of  gas  under 
other  conditions.  In  adjusting  a  multiple  jet  carburetor 
in  which  the  jets  are  provided  with  gasoline  regulating 
needles,  it  is  customary  to  consider  each  nozzle  as  a  dis- 
tinct carburetor  and  to  regulate  it  to  secure  the  best  motor 
action  at  that  throttle  position  which  corresponds  to  the 
conditions  under  which  the  jet  is  brought  into  service. 
For  instance,  that  supplied  the  primary  mixing  chamber 


Ball  and  Ball  Two-Stage  Carburetor 


131 


should  be  regulated  with  the  throttle  partly  closed,  while 
the  auxiliary  jet  should  be  adjusted  with  the  throttle  fully 
opened. 

BALL  AND   BALL   TWO-STAGE    CARBURETOR 

This  is  a  two-stage  vaporizing  device,  hot  air  being 
used  in  the  primary  or  initial  stage  of  vaporization  and 
cold  air  in  the  supplementary  stage.  Eeferring  to  the 
sectional  illustration  at  Fig.  48,  it  will  be  seen  that  there 


Fig.  48. — The  Ball  and  Ball  Two-Stage  Carburetor. 

is  a  hot-air  passage  with  a  choke-valve;  the  primary  ven- 
turi  appears  at  B ;  J  is  its  gasoline  jet,  and  V  is  a  spring- 
loaded  idling  valve  in  a  fixed  air  opening.  These  parts 
constitute  the  primary  system.  In  the  secondary  system 
A  is  a  cold-air  passage,  T  a  butterfly  valve  and  J  a  gaso- 
line jet  discharging  into  the  cold-air  passage.  This  sys- 
tem is  brought  into  operation  by  opening  the  butterfly  T. 
A  connection  between  the  butterfly  T  and  the  throttle,  not 
shown,  throws  the  butterfly  wide  open  when  the  throttle 
is  not  quite  wide  open;  at  all  other  times  the  butterfly 


132  Aviation  Engines 

is  held  closed  by  a  spring.  The  cylindrical  chamber  at 
the  right  of  the  mixing  chamber  has  an  extension  E  of 
reduced  diameter  connecting  it  with  the  intake  manifold 
through  a  passage  D.  A  restricted  opening  connects  the 
float  chamber  with  the  cylindrical  chamber  so  that  the 
gasoline  level  is  the  same  in  both.  A  loosely  fitting  plun- 
ger P  in  the  cylindrical  chamber  has  an  upward  extension 
into  the  small  part  of  the  chamber.  0  is  a  small  air 
opening  and  M  is  a  passage  from  the  cylindrical  chamber 
to  the  mixing  chamber.  Air  constantly  passes  through 
this  when  the  carburetor  is  in  operation.  The  carburetor 
is  really  two  in  one.  The  primary  carburetor  is  made  up 
of  a  central  jet  in  a  venturi  passage.  The  float  chamber 
is  eccentric.  In  the  air  passage  there  is  a  fixed  opening, 
and  additional  air  is  taken  in  by  the  opening  through 
suction  of  a  spring-opposed  air  valve.  The  second  stage, 
which  comes  into  play  as  soon  as  the  carburetor  is  called 
upon  for  additional  mixture  above  low  medium  speeds, 
is  made  up  of  an  independent  air  passage  containing  an- 
other air  valve.  As  the  valve  is  opened  this  jet  is  un- 
covered, and  air  is  led  past  it.  For  easy  starting  an 
extra  passage  leads  from  the  float  bowl  passage  to  a  point 
above  the  throttle.  All  the  suction  falls  upon  this  passage 
when  the  throttle  is  closed.  The  passage  contains  a  plun- 
ger and  acts  as  a  pick-up  device.  When  the  vacuum  in- 
creases the  plunger  rises  and  shuts  off  the  flow  of  gasoline 
from  the  intake  passage.  As  the  throttle  is  opened  the 
vacuum  in  the  intake  passage  is  broken,  and  the  plunger 
falls,  causing  gasoline  to  gather  above  it.  This  is  imme- 
diately drawn  through  the  pick-up  passage  and  gives  the 
desired  mixture  for  acceleration. 

MASTER   MULTIPLE-JET   CARBURETOR 

This  carburetor,  shown  in  detail  in  Figs.  49  and  50, 
has  been  very  popular  in  racing  cars  and  aviation  engines 
because  of  exceptionally  good  pick-up  qualities  and  its 
thorough  atomization  of  fuel.  Its  principle  of  operation 
is  the  breaking  up  of  the  fuel  by  a  series  of  jets,  which 


Master  Multiple-Jet  Carburetor 


133 


vary  in  number  from  fourteen  to  twenty-one,  according 
to  the  size  of  the  carburetor.  These  are  uncovered  by 
opening  the  throttle,  which  is  curved — a  patented  feature 
— to  secure  the  correct  progression  of  jets.  The  carbu- 


S  A  E  Standard  Flan 


\ 


Damper  Operated  by  Control 

Acts  as  Variable 
Venturl  Controlling  Mixture. 

mm 


14  to  19  Fine  Holes 
Where  Fuel  Comes 
Out  of  Distributer 
as  Throttle  is  Opened 


Air 
Intake • 


Where  Fuel  Enters  Distributer 
First  Being  Thoroughly  Filtered 


-Normal  Running 


Starting 
Position 


Fig.  49. — The  Master  Carburetor. 

retor  has  an  eccentric  float  chamber,  from  which  the  gas- 
oline is  led  to  the  jet  piece  from  which  the  jets  stand  up 
in  a  row.  The  tops  of  these  jets  are  closed  until  the 
throttle  is  opened  far  enough  to  pass  them,  which  it  does 
progressively.  The  air  opening  is  at  the  bottom,  and  the 
throttle  opening  is  such  that  a  modified  venturi  is  formed. 


134 


Aviation  Engines 


The  throttle  is  carried  in  a  cylindrical  barrel  with  the  jets 
placed  below  it,  and  the  passage  from  the  barrel  to  the 
intake  is  arranged  so  that,  there  is  no  interruption  in  the 
flow.  For  easy  starting  a  dash-controlled  shutter  closes 


Rotary 

Throttle 


""—Filter  Screens 

Tube  Screen       -  Detachable  Trap 


Fig.  50. — Sectional  View  of  Master  Carburetor  Showing  Parts. 

off  the  air,  throwing  the  suction  on  the  jets,  thus  giving 
a  rich  mixture. 

The  only  adjustment  is  for  idling,  and  once  that  is 
fixed  it  need  never  be  touched.  This  is  in  the  form  of 
a  screw  and  regulates  the  position  of  the  throttle  when 
at  idling  position.  The  dash  control  has  high-speed,  nor- 
mal and  rich-starting  positions.  In  installing  the  Master 
carburetor  the  float  chamber  may  be  turned  either  toward 
the  radiator  or  driver's  seat.  If  the  float  is  turned  toward 
the  radiator,  however,  a  forward  lug  plate  should  be 
ordered ;  otherwise  it  will  be  difficult  to  install  the  control. 
The  throttle  lever  must  go  all  the  way  to  the  stop  lug 


Compound  Nozzle  Zenith  Carburetor  135 

or  maximum  power  will  not  be  secured.    In  adjusting  the 
idle  screw  it  is  .turned  in  for  rich  and  out  for  lean. 

COMPOUND    NOZZLE    ZENITH    CARBURETOR 

The  Zenith  carburetor,  shown  at  Fig.  51,  has  become 
very  popular  for  airplane  engine  use  because  of  its  sim- 
plicity, as  mixture  compensation  is  secured  by  a  compen- 
sating compound  nozzle  principle  that  works  very  well  in 
practice.  To  illustrate  this  principle  briefly,  let  us  con- 
sider the  elementary  type  of  carburetor  or  mixing  valve, 
as  shown  in  Fig.  52,  A.  It  consists  of  a  single  jet  or 
spraying  nozzle  placed  in  the  path  of  the  incoming  air 
and  fed  from  the  usual  float  chamber.  It  is  a  natural 


PRIMING  HOLE  U 


PRIMING  TUBE  J 

REGULATING 
SCREW  O 


BUTTERFLY  T 


SECONDARY 
WELL  P 


CHOKE  X 


CAP  JET  H 


MAIN  JET  O 


COMPENSATOR  I 


Fig.  51. — Sectional  View  of  Zenith  Compound  Nozzle  Compensating 

Carburetor. 


136 


Aviation  Engines 


UJ 


Action  of  Zenith  Carburetor  137 

inference  to  suppose  that  as  the  speed  of  the  motor  in- 
creases, both  the  flow  of  air  and  of  gasoline  will  increase 
in  the  same  proportion.  Unhappily,  such  is  not  the  case. 
There  is  a  law  of  liquid  bodies  which  states  that  the  flow 
of  gasoline  from  the  jet  increases  under  suction  faster 
than  the  flow  of  air,  giving  a  mixture  which  grows  richer 
and  richer — a  mixture  containing  a  much  higher  percent- 
age of  gasoline  at  high  suction  than  at  low.  The  tendency 
is  shown  by  the  accompanying  curve  (Fig.  52,  B),  which 
gives  the  ratio  of  gasoline  to  air  at  varying  speeds  from 
this  type  of  jet.  The  mixture  is  practically  constant  only 
between  narrow  limits  and  at  very  high  speed.  The  most 
common  method  of  correcting  this  defect  is  by  putting 
various  auxiliary  air  valves  which,  adding  air,  tends  to 
dilute  this  mixture  as  it  gets  too  rich.  It  is  difficult  with 
makeshift  devices  to  gauge  this  dilution  accurately  for 
every  motor  speed. 

Now,  if  we  have  a  jet  which  grows  richer  as  the  suction 
increases,  the  opposite  type  of  jet  is  one  which  would 
grow  leaner  under  similar  conditions.  Baverey,  the  in- 
ventor of  the  Zenith,  discovered  the  principle  of  the  con- 
stant flow  device  which  is  shown  in  Fig.  52,  C.  Here 
a  certain  fixed  amount  of  gasoline  determined  by  the  open- 
ing I  is  permitted  to  flow  by  gravity  into  the  well  J  open 
to  the  air.  The  suction  at  jet  H  has  no  effect  upon  the 
gravity  compensator  I  because  the  suction  is  destroyed 
by  the  open  well  J.  The  compensator,  then,  delivers  a 
steady  rate  of  flow  per  unit  of  time,  and  as  the  motor 
suction  increases  more  air  is  drawn  up,  while  the  amount 
of  gasoline  remains  the  same  and  the  mixture  grows 
poorer  and  poorer.  Fig.  52,  D,  shows  this  curve. 

By  combining  these  two  types  of  rich  and  poor  mixture 
carburetors  the  Zenith  compound  nozzle  was  evolved.  In 
Fig.  52,  E,  we  have  both  the  direct  suction  or  richer  type 
leading  through  pipe  E  and  nozzle  G  and  the  "constant 
flow"  device  of  Baverey  shown  at  J,  I,  K  and  nozzle  H. 
One  counteracts  the  defects  of  the  other,  so  that  from 
the  cranking  of  the  motor  to  its  highest  speed  there  is 


138 


Aviation  Engines 


a  constant  ratio  of  air  and  gasoline  to  supply  efficient 
combustion. 

In  addition  to  the  compound  nozzle  the  Zenith  is 
equipped  with  a  starting  and  idling  well,  shown  in  the 
cut  of  Model  L  carburetor  at  P  and  J.  This  terminates 
in  a  priming  hole  at  the  edge  of  the  butterfly  valve, 
where  the  suction  is  greatest  when  this  valve  is  slightly 
open.  The  gasoline  is  drawn  up  by  the  suction  at  the 
priming  hole  and,  mixed  with  the  air  rushing  by  the  but- 
terfly, gives  an  ideal  slow  speed  mixture.  At  higher  speeds 


Mixing 

Chambers-' 


Float  JBowh^ 
Cover       \ 


Flood 

Bowl -> 


Fuel  Inlet 


Thro-H-le  Discs 


ThroH/e 

Lever 


.-Air  Intake 


Fig.  53. — The  Zenith  Duplex  Carburetor  for  Airplane  Motors  of  the  V  Type. 

with  the  butterfly  valve  opened  further  the  priming  well 
ceases  to  operate  and  the  compound  nozzle  drains  the  well 
and  compensates  correctly  for  any  motor  speed. 

With  the  coming  of  the  double  motor  containing  eight 
or  twelve  cylinders  arranged  in  two  V  blocks,  the  question 
of  good  carburetion  has  been  a  problem  requiring  much 
study.  The  single  carburetor  has  given  only  indifferent 
results  due  to  the  strong  cross  suction  in  the  inlet  mani- 
fold from  one  set  of  cylinders  to  the  other.  This  natur- 
ally led  to  the  adoption  of  two  carburetors  in  which  each 
set  of  cylinders  was  independently  fed  by  a  separate  car- 


Zenith  Carburetor  Installation 


139 


buretor.  Besults  from  this  system  were  very  good  when 
the  two  carburetors  were  working  exactly  in  unison,  but 
as  it  was  extremely  difficult  to  accomplish  this  co-opera- 
tion, especially  where  the  adjustable  type  was  employed, 


,lntake  Pipe 


Air 
Stove 


Centrifugal 
Water  Pump 


Flexible 
Air  Pipe- 


Jacketed  Manifold/ 
or  Y  Branch 


Air  Stove1 
Surrounding 
Exhaust  Pipes 


Water  Pipes 
to  Jacket 


Flexible 
Air  Pipe 


Zenith  Duplex 
Carburetor 


Fig.    54. — Rear   View    of    Curtiss    OX2    90    Horse-Power    Airplane    Motor 
Showing  Carburetor  Location  and  Hot  Air  Leads. 

this  system  never  gained  in  favor.  The  next  logical  step 
was  the  Zenith  Duplex,  shown  at  Fig.  53.  This  consists 
of  two  separate  and  distinct  carburetors  joined  together 
so  that  a  common  gasoline  float  chamber  and  air  inlet 
could  be  used  by  both.  It  does  away  with  cross  suction 
in  the  manifold  because  each  set  of  cylinders  has  a  sep- 


140  Aviation  Engines 

arate  intake  of  its  own.  It  does  away  with  two  carburet- 
ors and  makes  for  simplicity.  The  practical  application 
of  the  Zenith  carburetor  to  the  Curtiss  90  horse-power 
OX2  motor  used  on  the  J.N.4  standard  training  machine 
is  shown  at  Fig.  54,  which  outlines  a  rear  view  of  the 
engine  in  question.  The  carburetor  is  carried  low  to  per- 
mit of  fuel  supply  from  a  gravity  tank  carried  back  of 
the  motor. 

UTILITY    OF    GASOLINE    STRAINERS  J    •    ' 

Many  carburetors  include  a  filtering  screen  at  the  point 
where  the  liquid  enters  the  float  chamber  in  order  to  keep 
dirt  or  any  other  foreign  matter  which  may  be  present 
in  the  fuel  from  entering  the  float  chamber.  This  is  not 
general  practice,  however,  and  the  majority  of  vaporizers 
do  not  include  a  filter  in  their  construction.  It  is  very 
desirable  that  the  dirt  should  be  kept  out  of  the  carbu- 
retor because  it  may  get  under  the  float  control  fuel  valve 
and  cause  flooding  by  keeping  it  raised  from  its  seat.  If 
it  finds  its  way  into  the  spray  nozzle  it  may  block  the 
opening  so  that  no  gasoline  will  issue  .or  may  so  constrict 
the  passage  that  only  very  small  quantities  of  fuel  will 
be  supplied  the  mixture.  Where  the  carburetor  itself  is 
not  provided  with  a  filtering  screen  a  simple  filter  is 
usually  installed  in  the  pipe  line  between  the  gasoline 
tank  and  the  float  chamber. 

Some  simple  forms  of  filters  and  separators  are  shown 
at  Fig.  55.  That  at  A  consists  of  a  simple  brass  casting 
having  a  readily  detachable  gauze  screen  and  a  settling 
chamber  of  sufficient  capacity  to  allow  the  foreign  matter 
to  settle  to  "the  bottom,  from  which  it  is  drained  out  by 
a  pet  cock.  Any  water  or  dirt  in  the  gasoline  will  settle 
to  the  bottom  of  the  chamber,  and  as  all  fuel  delivered 
to  the  carburetor  must  pass  through  the  wire  gauze  screen 
it  is  not  likely  to  contain  impurities  when  it  reaches  the 
float  chamber.  The  heavier  particles,  such  as  scale  from 
the  tank  or  dirt  and  even  water,  all  of  which  have  greater 
weight  than  the  gasoline,  will  sink  to  the  bottom  of  the 


Utility  of  Gasoline  Strainers 


141 


chamber,  whereas  light  particles,  such  as  lint,  will  be  pre- 
vented from  flowing  into  the  carburetor  by  the  filtering 
screen. 

The  filtering  device  shown  at  B  is  a  larger  appliance 
than  that  shown  at  A,  and  should  be  more  efficient  as  a 


Supporting  Boss 


Gasoline 
from  Tank 


Gasoline 
from  Tank 


To  Carburetor 

Wire  Gauze 


To  Carburetor 


Wire  Gauze 

Settling  Chambe 
Settling  Chamber 


B 


Gasoline  Tan  ft 


Gasolin 
from  Tank 


To  Carburetor 


Wire  Gauze 

To  Carburetor. 


Settling  Chamber 

Settling  Chamber 


D 


Fig.  55. — Types  of  Strainers  Interposed  Between  Vaporizer  and  Gasoline 
Tank  to  Prevent  Water  or  Dirt  Passing  Into  Carbureting  Device. 

separator  because  the  gasoline  is  forced  to  pass  through 
three  filtering  screens  before  it  reaches  the  carburetor. 
The  gasoline  enters  the  device  shown  at  C  through  a  bent 
pipe  which  leads  directly  to  the  settling  chamber  and 
from  thence  through  a  wire  gauze  screen  to  the  upper 
compartment  which  leads  to  the  carburetor.  The  device 
shown  at  D  is  a  combination  strainer,  drain,  and  sedi- 


142  Aviation  Engines  • 

merit  cup.  The  filtering  screen  is  held  in  place  by  a 
spring  and  both  are  removed  by  taking  out  a  plug  at  the 
bottom  of  the  device.  The  shut-off  valve  at  the  top  of 
the  device  is  interposed  between  the  sediment  cup  and 
the  carburetor.  This  separating  device  is  incorporated 
with  the  gasoline  tank  and  forms  an  integral  part  of  the 
gasoline  supply  system.  The  other  types  shown  are  de- 
signed to  be  interposed  between  the  gasoline  tank  and 
the  carburetor  at  any  point  in  the  pipe  line  where  they 
may  be  conveniently  placed. 

INTAKE    MANIFOLD   DESIGN   AND    CONSTRUCTION 

On  four-  and  six-cylinder  engines  and  in  fact  on  all 
multiple-cylinder  forms,  it  is  important  that  the  piping 
leading  from  the  carburetor  to  the  cylinders  be  made  in 
such  a  way  that  the  various  cylinders  will  receive  their 
full  quota  of  gas  and  that  each  cylinder  will  receive  its 
charge  at  about  the  same  point  in  the  cycle  of  operations. 
In  order  to  make  the  passages  direct  the  bends  should 
be  as  few  as  possible,  and  when  curves  are  necessary  they 
should  be  of  large  radius  because  an  abrupt  corner  will  not 
only  impede  gas  flow  but  will  tend  to  promote  condensation 
of  the  fuel.  Every  precaution  should  be  taken  with  f our- 
and  six-cylinder  engines  to  insure  equitable  gas  distri- 
bution to  the  valve  chambers  if  regular  action  of  the 
power  plant  is  desired.  If  the  gas  pipe  has  many  turns 
and  angles  it  will  be  difficult  to  charge  all  cylinders  prop- 
erly. On  some  six-cylinder  aviation  engines,  two  carbu- 
retors are  used  because  of  trouble  experienced  with  man- 
ifolds designed  for  one  carburetor.  Duplex  carburetors 
are  necessary  to  secure  the  best  results  from  eight-  and 
twelve-cylinder  V  engines. 

The  problem  of  intake  piping  is  simplified  to  some 
extent  on  block  motors  where  the  intake  passage  is  cored 
in  the  cylinder  casting  and  \vhere  but  one  short  pipe  is 
needed  to  join  this  passage  to  the  carburetor.  If  the 
cylinders  are  cast  in  pairs  a  simple  pipe  of  T  or  Y  form 
can  be  used  with  success.  When  the  engine  is  of  a  type 


Intake  Manifold  Construction  143 

using  individual  cylinder  castings,  especially  in  the  six- 
cylinder  power  plants,  the  proper  application  and  instal- 
lation of  suitable  piping  is  a  difficult  problem.  The  reader 
is  referred  to  the  various  engine  designs  outlined  to  as- 
certain how  the  inlet  piping  has  been  arranged  on  repre- 
sentative aviation  engines.  Intake  piping  is  constructed 
in  two  ways,  the  most  common  method  being  to  cast  the 
manifold  of  brass  or  aluminum.  The  other  method,  which 
is  more  costly,  is  to  use  a  built-up  construction  of  copper 
or  brass  tubing  with  cast  metal  elbows  and  Y  pieces.  One 
of  the  disadvantages  advanced  against  the  cast  manifold 
is  that  blowholes  may  exist  which  produce  imperfect  cast- 
ings and  which  will  cause  mixture  troubles  because  the 
entering  gas  from  the  carburetor,  which  may  be  of  proper 
proportions,  is  diluted  by  the  excess  air  which  leaks  in 
through  the  porous  casting.  Another  factor  of  some  mo- 
ment is  that  the  roughness  of  the  walls  has  a  certain 
amount  of  friction  which  tends  to  reduce  the  velocity  of 
the  gases,  and  when  projecting  pieces  are  present,  such 
as  core  wire  or  other  points  of  metal,  these  tend  to  collect 
the  drops  of  liquid  fuel  and  thus  promote  condensation. 
The  advantage  of  the  built-up  construction  is  that  the 
walls  of  the  tubing  are  very  smooth,  and  as  the  castings 
are  small  it  is  not  difficult  to  clean  them  out  thoroughly 
before  they  are  incorporated  in  the  manifold.  The  tubing 
and  castings  are  joined  together  by  hard  soldering,  braz- 
ing or  autogenous  welding. 

COMPENSATING   FOR   VARYING    ATMOSPHERIC    CONDITIONS 

The  low-grade  gasoline  used  at  the  present  time  makes 
it  necessary  to  use  vaporizers  that  are  more  susceptible 
to  atmospheric  variations  than  when  higher  grade  and 
more  volatile  liquids  are  vaporized.  Sudden  temperature 
changes,  sometimes  being  as  much  as  forty  degrees  rise 
or  fall  in  twelve  hours,  affect  the  mixture  'proportions  to 
some  extent,  and  not  only  changes  in  temperature  but 
variations  in  altitude  also  have  a  bearing  on  mixture  pro- 
portions by  affecting  both  gasoline  and  air.  As  the  tern- 


144 


Aviation  Engines 


perature  falls  the  specific  gravity  of  the  gasoline  increases 
and  it  becomes  heavier,  this  producing  difficulty  in  vapor- 
izing. The  tendency  of  very  cold  air  is  to  condense  gas- 
oline instead  of  vaporizing  it  and  therefore  it  is  necessary 
to  supply  heated  air  to  some  carburetors  to  obtain  proper 
mixtures  during  cold  weather.  In  order  that  the  gas  mix- 
tures will  ignite  properly  the  fuel  must  be  vaporized  and 
thoroughly  mixed  with  the  entering  air  either  by  heat  or 


Atmospheric  Pressure,  Ibs.  per  sq.in. 
^oi  5  <£  F3  —  o  CP  o 

^ 

^ 

^^ 

'^# 

^ 

^^ 

&* 

^ 

^ 

^ 

/?. 

)                     ZOOO                  4000                   6000                    8000                  10.000 
Altitude  in  Feet    Above  Sea  Level 

Fig.  56.— Chart  Showing  Diminution  of  Air  Pressure  as  Altitude  Increases. 

high  velocity  of  the  gases.  The  application  of  air  stoves 
to  the  Curtiss*  0X2  motor  is  clearly  shown  at  Fig.  54.  It 
will  be  seen  that  flexible  metal  pipes  are  used  to  convey 
the  heated  air  to  the  air  intakes  of  the  duplex  mixing 
chamber. 

HOW    HIGH    ALTITUDE    AFFECTS    POWER 

Any  internal  combustion  engine  will  show  less  power 
at  high  altitudes  than  it  will  deliver  at  sea  level,  and  this 
has  caused  a  great  deal  of  questioning.  "There  is  a  good 


How  High  Altitude  Affects  Power  145 

reason  for  this,"  says  a  writer  in  " Motor  Age,"  "and 
it  is  a  physical  impossibility  for  the  engine  to  do  other- 
wise. The  difference  is  due  to  the  lower  atmospheric 
pressure  the  higher  up  we  get.  That  is,  at  sea  level  the 
atmosphere  has  a  pressure  of  14.7  pounds  per  square  inch ; 
at  5,000  feet  above  sea  level  the  pressure  is  approximately 
12.13  pounds  per  square  inch,  and  at  10,000  feet  it  is  10 
pounds  per  square  inch.  From  this  it  will  be  seen  that 
the  final  pressure  attained  after  the  piston  has  driven 
the  gas  into  compressed  condition  ready  for  firing  is  lower 
as  the  atmospheric  pressure  drops.  This  means  that  there 
is  not  so  much  power  in  the  compressed  charge  of  gas  the 
higher  up  you  get  above  sea  level. 

"For  example,  suppose  the  compression  ratio  to  be 
4^2  to  1;  in  other  words,  suppose  the  air  space  above  the 
piston  to  have  4^  times  the  volume  when  the  piston  is 
at  the  bottom  of  its  stroke  that  it  has  when  the  piston  is 
at  the  top  of  the  stroke.  That  is  a  common  compression 
ratio  for  an  average  motor,  and  is  chosen  because  it  is 
considered  to  be  the  best  for  maximum  horse-power  and 
in  order  that  the  compression  pressure  will  not  be%so  high 
as  to  cause  pre-ignition.  Knowing  the  compression  ratio, 
we  can  determine  the  final  pressure  immediately  before 
ignition  by  substituting  in  the  standard  formula: 


1.3 


in  which  P  is  the  atmospheric  pressure;  P1  is  the  final 

V 

pressure,  and  —  is  the  compression  ratio,  therefore  P1  = 
V1 

14.7  (4.5)1>3=  104  pounds  per  square  inch,  absolute. 

"That  is,  104  pounds  per  square  inch  is  the  most  effi- 
cient final  compression  pressure  to  have  for  this  engine 
at  sea  level,  since  it  comes  directly  from  the  compression 
ratio. 

"Now  supposing  we  consider  that  the  altitude  is  7,000 


146  Aviation  Engines 

feet  above  sea  level.  At  this  height  the  atmospheric  press- 
ure is  11.25  pounds  per  square  inch,  approximately.  In 
this  case  we  can  again  substitute  in  the  formula,  using 
the  new  atmospheric  pressure  figure.  The  equation  be- 
comes : 

P1— 11.25  ( 4.5)  i-3— 79.4  pounds  per  square  inch,  ab- 
solute. 

"Therefore  we  now  have  a  final  compression  pressure 
of  only  79.4  pounds  per  square  inch,  which  is  considerably 
below  the  pressure  we  have  just  found  to  be  the  most 
efficient  for  the  motor.  The  resulting  power  drop  is  evi- 
dent. 

"It  should  be  borne  in  mind  that  these  final  compres- 
sion pressures  are  absolute  pressures — that  is,  they  in- 
clude the  atmospheric  pressure.  In  the  first  case,  to  get 
the  pressure  above  atmospheric  you  would  subtract  14.7 
and  in  the  latter  11.25  would  have  to  be  deducted.  In 
other  words,  where  the  sea  level  compression  is  89.3  pounds 
per  square  inch  above  the  atmosphere,  the  same  motor 
will  hav,e  only  a  compression  pressure  of  68.15  pounds 
per  square  inch  above  the  atmosphere  at  7,000  feet  ele- 
vation. • 

"From  the  above  it  is  evident  that  in  order  to  bring 
the  final  compression  pressure  up  to  the  efficient  figure 
we  have  determined,  a  different  compression  ratio  would 
have  to  be  used.  That  is,  the  final  volume  would  have 
to  be  less,  and  as  it  is  impossible  to  vary  this  to  meet 
the  conditions  of  altitude,  the  loss  of  power  cannot  be 
helped  except  by  the  replacing  of  the  standard  pistons 
with  some  that  are  longer  above  the  wrist-pin  so  as  to 
reduce  the  space  above  the  pistons  when  on  top  center. 
Then  if  the  ratio  is  thereby  raised  to  some  such  figures 
as  5  to  1,  the  engine  will  again  have  its  proper  final  press- 
ure, but  it  will  still  not  have  as  much  power  as  it  would 
have  at  sea  level,  since  the  horse-power  varies  directly 
with  the  atmospheric  pressure,  final  compression  being 
kept  constant.  That  is,  at  7,000  feet  the  horse-power  of 


The  Diesel  System  147 

an  engine  that  had  40  horse-power  at  sea  level  would  be 
equal  to 

11.25 

-  —  30 . 6  horse-power. 

14.7 

"If  the  original  compression  ratio  of  4.5  were  retained, 
the  drop  in  horse-power  would  be  even  greater  than  this. 
These  computations  and  remarks  will  make  it  clear  that 
the  designer  who  contemplates  building  an  airplane  for 
high  altitude  use  should  see  to  it  that  it  is  of  sufficient 
power  to  compensate  for  the  drop  that  is  inevitable  when 
it  is  up  in  the  air.  This  is  often  illustrated  in  stationary 
gas-engine  installations.  An  engine  that  had  a  sea-level 
rating  amply  sufficient  for  the  work  required,  might  not 
be  powerful  enough  when  brought  up  several  thousand 
feet."  When  one  considers  that  airplanes  attain  heights 
of  over  18,000  feet,  it  will  be  evident  that  an  ample  mar- 
gin of  engine  power  is  necessary, 

THE  DIESEL  SYSTEM 

A  system  of  fuel  supply  developed  by  the  late  Dr. 
Diesel,  a  German  chemist  and  engineer,  is  attracting  con- 
siderable attention  at  the  present  time  on  account  of  the 
ability  of  the  Diesel  engine  to  burn  low-grade  fuels,  such 
as  crude  petroleum.  In  this  system  the  engines  are  built 
so  that  very  high  compressions  are  used,  and  only  pure 
air  is  taken  into  the  cylinder  on  the  induction  stroke. 
This  is  compressed  to  a  pressure  of  about  500  pounds 
per  square  inch,  and  sufficient  heat  is  produced  by  this 
compression  to  explode  a  hydrocarbon  mixture.  As  the 
air  which  is  compressed  to  this  high  point  cannot  burn, 
the  fuel  is  introduced  into  the  cylinder  combustion  cham- 
ber under  still  higher  compression  than  that  of  the  com- 
pressed air,  and  as  it  is  injected  in  a  fine  stream  it  is 
immediately  vaporized  because  of  the  heat.  Just  as  soon 
as  the  compressed  air  becomes  thoroughly  saturated  with 
the  liquid  fuel,  it  will  explode  on  account  of  the  degree  of 


148  Aviation  Engines 

heat  present  in  the  combustion  chamber.  Such  motors 
have  been  used  in  marine  and  stationary  applications,  but 
are  not  practical  for  airplanes  or  motor  cars  because  of 
lack  of  flexibility  and  great  weight  in  proportion  to  power 
developed.  The  Diesel  engine  is  the  standard  power  plant 
used  in  submarine  boats  and  motor  ships,  as  its  efficiency 
renders  it  particularly  well  adapted  for  large  units. 

NOTES    ON    CAKBUKETOK    INSTALLATION    IN    AIRPLANES 

A  writer  in  "The  Aeroplane,"  an  English  publication, 
discourses  on  some  features  of  carburetor  installation  that 
may  be  of  interest  to  the  aviation  student,  so  portions  of 
the  dissertation  are  reproduced  herewith. 

"  Users  of  airplanes  fitted  with  ordinary  type  carburetors  will 
do  well  to  note  carefully  the  way  in  which  these  are  fitted,  for 
several  costly  machines  have  been  burnt  lately  through  the  sheer 
carelessness  of  their  users.  These  particular  machines  were  fitted 
with  a  high  powered  V-type  engine,  made  by  a  firm  which  is 
famous  as  manufacturers  of  automobiles  de  luxe.  In  these  engines 
there  are  four  carburetors,  mounted  in  the  V  between  the  cylinders. 
When  the  engine  is  fitted  as  a  tractor,  the  float  chambers  are  in 
front  of  the  jet  chambers.  Consequently,  when  the  tail  of  the 
machine  is  resting  on  the  ground,  the  jets  are  lower  than  the  level 
of  the  gasoline  in  the  float  chamber. 

"Quite  naturally,  the  gasoline  runs  out  of  the  jet,  if  it  is  left 
turned  on  when  the  machine  is  standing  in  its  normal  position, 
and  trickles  into  the  V  at  the  top  of  the  crank-case.  Thence  it 
runs  down  to  the  tail  of  the  engine,  where  the  magnetos  are  fitted; 
and  saturates  them.  If  left  long  enough,  the  gasoline  manages 
to  soak  well  into  the  fuselage  before  evaporating.  And  what  does 
evaporate  makes  an  inflammable  gas  in  the  forward  cockpit.  Then 
some  one  comes  along  and  starts  up  the  engine.  The  spark-gap 
of  the  magneto  gives  one  flash,  and  the  whole  front  of  the  machine 
proceeds  to  give  a  Fourth  of  July  performance  forthwith.  Natu- 
rally, one  safeguard  is  to  turn  the  petrol  off  directly  the  machine 
lands.  Another  is  never  to  turn  it  on  till  the  engine  is  actually 
being  started  up. 

"One  would  be  asking  too  much  of  the  human  boy — who  is 
officially  regarded  as  the  only  person  fit  to  fly  an  aeroplane — if 
one  depended  upon  his  memory  of  such  a  detail  to  save  his  ma- 
chine, though  one  might  perhaps  reasonably  expect  the  older  pilots 
to  remember  not  to  forget.  Even  so,  other  means  of  prevention 


Notes  on  Carburetor  Installation  149 

are  preferable,  for  fire  is  quite  as  likely  to  occur  from  just  the 
same  cause  if  the  engine  happens  to  be  a  trifle  obstinate  in  start- 
ing, and  so  gives  the  carburetors  several  minutes  in  which  to  drip 
— in  which  operation  they  would  probably  be  assisted  by  air- 
mechanics  'tickling'  them. 

"One  way  out  of  the  trouble  is  to  fit  drip  tins  under  the  jet 
chamber  to  catch  the  gasoline  as  it  falls.  This  is  all  very  well 
just  to  prevent  fire  while  the  machine  is  being  started  up,  but  it 
will  not  save  it  if  it  is  left  standing  with  the  tail  on  the  ground 
and  the  petrol  turned  on,  for  the  drip  tins  will  then  fill  up  and 
run  over.  And  if  it  catches  then,  the  contents  of  the  drip  tins 
merely  add  fuel  to  the  fire. 

Reversing  Carburetors 

"Yet  another  way  is  to  turn  the  carburetors  round,  so  that 
the  float  chambers  are  behind  the  jets,  and  so  come  below  them 
when  the  tail  is  on  the  ground,  thus  cutting  off  the  gasoline  low 
down  in  the  jets.  There  seems  to  be  no  particular  mechanical 
difficulty  about  this,  though  I  must  confess  that  I  did  not  note 
very  carefully  whether  the  reversal  of  the  float  chambers  would 
make  them  foul  any  other  fittings  on  the  engine.  It  has  been 
argued,  however,  that  doing  this  would  starve  the  engine  of  gaso- 
line when  climbing  at  a  steep  angle,  as  the  gasoline  would  then 
be  lowered  in  the  jets  and  need  more  suction  to  get  into  the 
cylinders.  This  is  rather  a  pretty  point  of  amateur  motor  me- 
chanics to  discuss,  for,  obviously,  when  the  same  engine  is  used 
as  a  'pusher'  instead  of  a  tractor,  the  jets  are  in  front  of  the 
floats,  and  there  seems  to  be  no  falling  off  in  power. 

Starvation  of  Mixture 

"Moreover,  the  higher  a  machine  goes  the  lower  is  the  atmos- 
pheric pressure,  and,  consequently,  the  less  is  the  amount  of  air 
sucked  in  at  each  induction  stroke.  This  means,  of  course,  that 
with  the  gasoline  supply  the  mixture  at  high  altitudes  is  too 
rich,  so  that,  in  order  to  get  precisely  the  right  mixture  when  very 
high  up,  it  is  necessary  to  reduce  the  gasoline  supply  by  screwing 
down  the  needle  valve  between  the  tank  and  the  carburetor — at 
least,  that  has  been  the  experience  of  various  high-flying  pilots. 
No  doubt  something  might  be  done  in  the  way  of  forced  air  feed 
to  compensate  for  reduced  atmospheric  pressure,  but  it  remains 
to  be  proved  whether  the  extra  weight  of  mechanism  involved 
would  pay  for  the  extra  power  obtained.  Variable  compression 
might  do  something,  also,  to  even  things  up,  but  here,  also,  weight- 
of  mechanism  has  to  be  considered. 

"In  any  case,  at  present,  the  higher  one  goes  the  more  the 


150  Aviation  Engines 

power  of  the  engine  is  reduced,  for  less  air  means  a  less  volume 
of  mixture  per  cylinder,  and  as  the  petrol  feed  has  to  be  starved 
to  suit  the  smaller  amount  of  air  available,  this  means  further  loss 
of  power.  I  do  not  know  whether  anyone  has  evolved  a  carbu- 
retor which  automatically  starves  the  gasoline  feed  when  high  up, 
but  it  seems  possible  that  when  an  airplane  is  sagging  about  'up 
against  the  ceiling' — as  a  French  pilot  described  the  absolute 
limit  of  climb  for  his  particular  machine — it  might  be  a  good 
thing  to  have  the  jets  in  front  of  the  float  chamber,  for  then  a 
certain  amount  of  automatic  starvation  would  take  place. 

"When  a  machine  is  right  up  at  its  limiting  height,  and  the 
pilot  is  doing  his  best  to  make  it  go  higher  still,  it  is  probably 
flying  with  its  tail  as  low  as  the  pilot  dares  to  let  it  go,  and  the 
lateral  and  longitudinal  controls  are  on  the  verge  of  vanishing, 
so  that  if  the  carburetor  jets  are  behind  the  float  chambers  there 
is  bound  to  be  an  over-rich  mixture  in  any  case.  There  is  even 
a  possibility  of  a  careless  or  ignorant  pilot  carrying  on  in  this  tail- 
down  position  till  one  set  of  cylinders  cuts  out  altogether,  in  which 
case  the  carburetor  feeding  that  set  may  flood  over,  just  as  if  the 
machine  were  on  the  ground,  and  the  whole  thing  may  catch  fire. 
Whereas,  with  the  jets  in  front  of  the  floats,  though  the  mixture 
may  starve  a  trifle,  there  is,  at  any  rate,  no  danger  of  fire  through 
climbing  with  the  tail  down. 

A  Diving  Danger 

"On  the  other  hand,  in  a  'pusher'  with  this  type  of  engine, 
if  the  jets  are  in  their  normal  position — which  is  in  front  of  the 
floats — there  is  danger  of  fire  in  a  dive.  That  is  to  say,  if  the 
pilot  throttles  right  down,  or  switches  off  and  relies  on  air  pres- 
sure on  his  propeller  to  start  the  engine  again,  so  that  the  gasoline 
is  flooding  over  out  of  the  jets  instead  of  being  sucked  into  the 
engine,  there  may  be  flooding  over  the  magnetos  if  the  dive  is  very 
steep  and  prolonged.  In  any  case,  a  long  dive  will  mean  a  certain 
amount  of  flooding,  and,  probably,  a  good  deal  of  choking  and 
spitting  by  the  engine  before  it  gets  rid  of  the  over-rich  mixture 
and  picks  up  steady  firing  again.  Which  may  indicate  to  young 
pilots  that  it  is  not  good  to  come  down  too  low  under  such  cir- 
cumstances, trusting  entirely  to  their  engines  to  pick  up  at  once 
and  get  going  before  they  hit  the  ground. 

' '  On  the  whole,  it  .seems  that  it  might  be  better  practice  to  set 
the  carburetors  thwartwise  of  engines,  for  then  jets  and  floats 
would  always  be  at  approximately  the  same  level,  no  matter  what 
the  longitudinal  position  of  the  machine,  and  it  is  never  long 
enough  in  one  positiqn  at  a  big  lateral  angle  to  raise  any  serious 
carburetor  troubles.  Car  manufacturers  who  dive  cheerfully  into 


Notes  on  Carburetor  Adjustment  151 

the  troubled  waters  of  aero-engine  designs  are  a  trifle  apt  to  forget 
that  their  engines  are  put  into  positions  on  airplanes  which 
would  be  positively  indecent  in  a  motor  car.  An  angle  of  1  in  10 
is  the  exception  on  a  car,  but  it  is  common  on  an  airplane,  and 
no  one  ever  heard  of  a  car  going  down  a  hill  of  10  to  1 — which  is 
not  quite  a  vertical  dive.  Therefore,  there  is  every  excuse  for  a 
well-designed  and  properly  brought-up  carburetor  misbehaving 
itself  in  an  aeroplane. 

"It  seems,  then,  that  it  is  up  to  the  manufacturers  to  produce 
better  carburetors — say,  with  the  jet  central  with  the  float.  But 
it  also  behooves  the  user  to  show  ordinary  common  sense  in  han- 
dling the  material  at  present  available,  and  not  to  make  a  prac- 
tice of  burning  up  $25,000  worth  or  so  of  airplane  just  because 
he  is  too  lazy  to  turn  off  his  gasoline,  or  to  have  the  tail  of  his 
machine  lifted  up  while  he  is  tinkering  with  his  engines. ' ' 

NOTES  ON  CARBURETOR  ADJUSTMENT 

The  modern  float  feed  carburetor  is  a  delicate  and 
nicely  balanced  appliance  that  requires  a  certain  amount 
of  attention  and  care  in  order  to  obtain  the  best  results. 
The  adjustments  can  only  be  made  by  one  possessing  an 
intelligent  knowledge  of  carburetor  construction  and  must 
never  be  made  unless  the  reason  for  changing  the  old  ad- 
justment is  understood.  Before  altering  the  adjustment 
of  the  leading  forms  of  carburetors,  a  few  hints  regarding 
the  quality  to  be  obtained  in  the  mixture  should  be  given 
some  consideration,  as  if  these  are  properly  understood 
this  knowledge  will  prove  of  great  assistance  in  adjusting 
the  vaporizer  to  give  a  good  working  proportion  of  fuel 
and  air.  There  is  some  question  regarding  the  best  mix- 
ture proportions  and  it  is  estimated  that  gas  will  be 
explosive  in  which  the  proportions  of  fuel  vapor  and  air 
will  vary  from  one  part  of  the  former  to  a  wide  range 
included  between  four  and  eighteen  parts  of  the  latter. 
A  one  to  four  mixture  is  much  too  rich,  while  the  one 
in  eighteen  is  much  too  lean  to  provide  positive  ignition. 

A  rich  mixture  should  be  avoided  because  the  excessive 
fuel  used  will  deposit  carbon  and  will  soot  the  cylinder 
walls,  combustion  chamber  interior,  piston  top  and  valves 
and  also  tend  to  overheat  the  motor.  A  rich  mixture  will 


152  Aviation  Engines 

also  seriously  interfere  with  flexible  control  of  the  engine, 
as  it  will  choke  up  on  low  throttle  and  run  well  on  open 
throttle  when  the  full  amount  of  gas  is  needed.  A  rich 
mixture  may  be  quickly  discovered  by  black  smoke  issuing 
from  the  muffler,  the  exhaust  gas  having  a  very  pungent 
odor.  If  the  mixture  contains  a  surplus  of  air  there  will 
be  popping  sounds  in  the  carburetor,  which  is  commonly 
termed  "blowing  back."  To  adjust  a  carburetor  is  not 
a  difficult  matter  when  the  purpose  of  the  various  control 
members  is  understood.  The  first  thing  to  do  in  adjusting 
a  carburetor  is  to  start  the  motor  and  to  retard  the  spark- 
ing lever  so  the  motor  will  run  slowly  leaving  the  throttle 
about  half  open.  In  order  to  ascertain  if  the  mixture  is 
too  rich  cut  down  the  gasoline  flow  gradually  by  screwing 
down  the  needle,  valve  until  the  motor  commences  to  run 
irregularly  or  misfire.  Close  the  needle  valves  as  far  as 
possible  without  having  the  engine  come  to  a  stop,  and 
after  having  found  the  minimum  amount  of  fuel  gradually 
unscrew  the  adjusting  valve  until  you  arrive  at  the  point 
where  the  engine  develops  its  highest  speed.  "When  this 
adjustment  is  secured  the  lock  nut  is  screwed  in  place  so 
the  needle  valve  will  keep  the  adjustment.  The  next  point 
to  look  out  for  is  regulation  of  the  auxiliary  air  supply  on 
those  types  of  carburetors  where  an  adjustable  air  valve 
is  provided.  This  is  done  by  advancing  the  spark  lever 
and  opening  the  throttle.  The  air  valve  is  first  opened 
or  the  spring  tension  reduced  to  a  point  where  the  engine 
misfires  or  pops  back  in  the  carburetor.  When  the  point 
of  maximum  air  supply  the  engine  will  run  on  is  thus  de- 
termined, the  air  valve  spring  may  be  tightened  by  screw- 
ing in  on  the  regulating  screw  until  the  point  is  reached 
where  an  appreciable  speeding  up  of  the  engine  is  noticed. 
If  both  fuel  and  air  valves  are  set  right,  it  will  be  possible 
to  accelerate  the  engine  speed  uniformly  without  interfer- 
ing with  regularity  of  engine  operation  by  moving  the 
throttle  lever  or  accelerator  pedal  from  its  closed  to  its 
wide  open  position,  this  being  done  with  the  spark  lever 
advanced.  All  types  of  carburetors  do  not  have  the  same 


Notes  on  Carburetor  Adjustment  153 

means  of  adjustment;  in  fact,  some  adjust  only  with  the 
gasoline  regulating  needle;  others  must  have  a  complete 
change  of  spray  nozzles;  while  in  others  the  mixture  pro- 
portions may  be  varied  only  by  adjustment  of  the  quantity 
of  entering  air.  Changing  the  float  level  is  effective  in 
some  carburetors,  but  this  should  never  be  done  unless  it 
is  certain  that  the  level  is  not  correct.  Full  instructions 
for  locating  carburetion  troubles  will  be  given  in  proper 
sequence. 

It  is  a  fact  well  known  to  experienced  repairmen  and 
motorists  that  atmospheric  conditions  have  much  to  do 
with  carburetor  action.  It  is  often  observed  that  a  motor 
seems  to  develop  more  power  at  night  than  during  the 
day,  a  circumstance  which  is  attributed  to  the  presence  of 
more  moisture  in  the  cooler  night  air.  Likewise,  taking 
a  motor  from  sea  level  to  an  altitude  of  10,000  feet  in- 
volves using  rarefied  air  in  the  engine  cylinders  and  at- 
mospheric pressures  ranging  from  14.7  pounds  at  sea 
level  to  10.1  pounds  per  square  inch  at  the  high  altitude. 
All  carburetors  will  require  some  adjustment  in  the  course 
of  any  material  change  from  one  level  to  another.  Great 
changes  of  altitude  also  have  a  marked  effect  on  the  cool- 
ing system  of  an  airplane.  Water  boils  at  212  degrees  F. 
only  at  sea  level.  At  an  altitude  of  10,000  feet  it  will, 
boil  at  a  temperature  nineteen  degrees  lower,  or  193  de- 
grees F. 

In  high  altitudes  the  reduced  atmospheric  pressure, 
for  5,000  feet  or  higher  than  sea  level,  results  in  not 
enough  air  reaching  the  mixture,  so  that  either  the  auxil- 
iary air  opening  has  to  be  increased,  or  the  gasoline  in 
the  mixture  cut  down.  If  the  user  is  to  be  continually 
at  high  altitudes  he  should  immediately  purchase  either 
a  larger  dome  or  a  smaller  strangling  tube,  mentioning 
the  size  carburetor  that  is  at  present  in  use  and  the  type 
of  motor  that  it  is  on,  including  details  as  to  the  bore 
and  stroke.  The  smaller  strangling  tube  makes  an  in- 
creased suction  at  the  spray  nozzle ;  the  air  will  have  to 
be  readjusted  to  meet  it  and  you  can  use  more  auxiliary 


154  Aviation  Engines 

air,  which  is  necessary.  The  effect  on  the  motor  without 
a  smaller  strangling  tube  is  a  perceptible  sluggishness  and 
failure  to  speed  up  to  its  normal  crank-shaft  revolutions, 
as  well  as  failure  to  give  power.  It  means  that  about  one- 
third  of  the  regular  speed  is  cut  out.  The  reduced  at- 
mospheric pressure  reduces  the  power  of  the  explosion, 
in  that  there  is  not  the  same  quantity  of  oxygen  in  the 
combustion  chamber  as  at  sea  level ;  to  increase  the  amount 
taken  in,  you  must  also  increase  the  gasoline  speed,  which 
is  done  by  an  increased  suction  through  the  smaller  stran- 
gling aperture.  Some  forms  of  carburetors  are  affected 
more  than  others  by  changes  of  altitude,  which  explains 
why  the  Zenith  is  so  widely  employed  for  airplane  engine 
use.  The  compensating  nozzle  construction  is  not  influ- 
enced as  much  by  changes  of  altitude  as  the  simpler  nozzle 
types  are. 


CHAPTER   VI 

Early  Ignition  Systems — Electrical  Ignition  Best — Fundamentals  of 
Magnetism  Outlined — Forms  of  Magneto — Zones  of  Magnetic  In- 
fluence— How  Magnets  are  Made — Electricity  and  Magnetism 
Related — Basic  Principles  of  Magneto  Action — Essential  Parts  of 
Magneto  and  Functions — Transformer  Coil  Systems — True  High 
Tension  Type — The  Berling  Magneto — Timing  and  Care— The 
Dixie  Magneto — Spark  Plug  Design  and  Application — Two-Spark 
Ignition — Special  Airplane  Plug. 

EAKLY  IGNITION  SYSTEMS  ,  % 

ONE  of  the  most  important  auxiliary  groups  of  the 
gasoline  engine  comprising  the  airplane  power  plant  and 
one  absolutely  necessary  to  insure  engine  action  is  the 
ignition  system  or  the  method  employed  of  kindling  the 
compressed  gas  in  the  cylinder  to  produce  an  explosion 
and  useful  power.  The  ignition  system  has  been  fully 
as  well  developed  as  other  parts  of  the  engine,  and  at 
the  present  time  practically  all  ignition  systems  follow 
principles  which  have  become  standard  through  wide  ac- 
ceptance. 

During  the  early  stages  of  development  of  the  gasoline 
engine  various  methods  of  exploding  the  charge  of  com- 
bustible gas  in  the  cylinder  were  employed.  On  some  of 
the  earliest  engines  a  flame  burned  close  to  the  cylinder 
head,  and  at  the  proper  time  for  ignition  a  slide  or  valve 
moved  to  provide  an  opening  which  permitted  the  flame 
to  ignite  the  gas  back  of  the  piston.  This  system  was 
practical  only  on  the  primitive  form  of  gas  engines  in 
which  the  charge  was  not  compressed  before  ignition. 
Later,  when  it  was  found  desirable  to  compress  the  gas 
a  certain  degree  before  exploding  it,  an  incandescent  plat- 
inum tube  in  the  combustion  chamber,  which  was  kept 
in  a  heated  condition  by  a  flame  burning  in  it,  exploded 
the  gas.  The  naked  flame  was  not  suitable  in  this  appli- 

155 


156  Aviation  Engines 

cation  because  when  the  slide  was  opened  to  provide  com- 
munication between  the  flame  and  the  gas  the  compressed 
charge  escaped  from  the  cylinder  with  enough  pressure  to 
blow  out  the  flame  at  times  and  thus  cause  irregular  ig- 
nition. When  the  flame  was  housed  in  a  platinum  tube 
it  was  protected  from  the  direct  action  of  the  gas,  and 
as  long  as  the  tube  was  maintained  at  the  proper  point 
of  incandescence  regular  ignition  was  obtained. 

Some  engineers  utilized  the  property  of  gases  firing 
themselves  if  compressed  to  a  sufficient  degree,  while 
others  depended  upon  the  heat  stored  in  the  cylinder-head 
to  fire  the  highly  compressed  gas.  None  of  these  methods 
were  practical  in  their  application  to  motor  car  engines 
becanise  they  did  not  permit  flexible  engine  action  which 
is  so  desirable.  At  the  present  time,  electrical  ignition 
systems  in  which  the  compressed  gas  is  exploded  by  the 
heating  value  of  the  minute  electric  arc  or  spark  in  the 
cylinder  are  standard,  and  the  general  practice  seems  to 
be  toward  the  use  of  mechanical  producers  of  electricity 
rather  than  chemical  batteries. 

ELECTRICAL    IGNITION    BEST 

Two  general  forms  of  electrical  ignition  systems  may 
be  used,  the  most  popular  being  that  in  which  a  current 
of  electricity  under  high  tension  is  made  to  leap  a  gap 
or  air  space  between  the  points  of  the  sparking  plug 
screwed  into  the  cylinder.  The  other  form,  which  has 
been  almost  entirely  abandoned  in  automobile  and  which 
was  never  used  with  airplane  engine  practice,  but  which 
is  still  used  to  some  extent  on  marine  engines,  is  called 
the  low-tension  system  because  current  of  'low  voltage  is 
used  and  the  spark  is  produced  by  moving  electrodes  in 
the  combustion  chamber. 

The  essential  elements  of  any  electrical  ignition  sys- 
tem, either  high  or  low  tension,  are:  First,  a  simple  and 
practical  method  of  current  production;  second,  suitable 
timing  apparatus  to  cause  the  spark  to  occur  at  the  right 
point  in  the  cycle  of  engine  action;  third,  suitable  wiring 


Fundamentals  of  Magnetism  157 

and  other  apparatus  to  convey  the  current  produced  by 
the  generator  to  the  sparking  member  in  the  cylinder. 

The  various  appliances  necessary  to  secure  prompt  ig- 
nition of  the  compressed  gases  should  be  described  in  some 
detail  because  of  the  importance  of  the  ignition  system. 
It  is  patent  that  the  scope  of  a  work  of  this  character 
does  not  permit  one  to  go  fully  into  the  theory  and  prin- 
ciples of  operation  of  all  appliances  which  may  be  used 
in  connection  with  gasoline  motor  ignition,  but  at  the  same 
time  it  is  important  that  the  elementary  principles  be 
considered  to  some  extent  in  order  that  the  reader  should 
have  a  proper  understanding  of  the  very  essential  ignition 
apparatus.  The  first  point  considered  will  be  the  common 
methods  of  generating  the  electricity,  then  the  appliances 
to  utilize  it  and  produce  the  required  spark  in  the  cylin- 
der. Inasmuch  as  magneto  ignition  is  universally  used 
in  connection  with  airplane  engine  ignition  it  will  not  be 
necessary  to  consider  battery  ignition  systems. 

FUNDAMENTALS    OF    MAGNETISM    OUTLINED 

To  properly  understand  the  phenomena  and  forces  in- 
volved in  the  generation  of  electrical  energy  by  mechanical 
means  it  is  necessary  to  become  familiar  with  some  of  the 
elementary  principles  of  magnetism  and  its  relation  to 
electricity.  The  following  matter  can  be  read  with  profit 
by  those  who  are  not  familiar  with  the  subject.  Most 
persons  know  that  magnetism  exists  in  certain  substances, 
but  many  are  not  able  to  grasp  the  terms  used  in  describ- 
ing the  operation  of  various  electrical  devices  because  of 
not  possessing  a  knowledge  of  the  basic  facts  upon  which 
the  action  of  such  apparatus  is  based. 

Magnetism  is  a  property  possessed  by  certain  sub- 
stances and  is  manifested  by  the  ability  to  attract  and 
repel  other  materials  susceptible  to  its  effects.  "When  this 
phenomenon  is  manifested  by  a  conductor  or  wire  through 
which  a  current  of  electricity  is  flowing  it  is  termed  "elec- 
tro-magnetism." Magnetism  and  electricity  are  closely 
related,  each  being  capable  of  producing  the  other.  Prac- 


160  Aviation  Engines 

the  size  of  the  magnets  used  and  the  air  gap  separating 
the  poles.  If  the  south  pole  of  one  magnet  is  brought 
close  to  the  end  of  the  same  polarity  of  the  other  there 
will  be  a  pronounced  repulsion  of  like  force.  These  facts 
are  easily  proved  by  the  simple  experiment  outlined  at 
B,  Fig.  57.  A  magnet  will  only  attract  or  influence  a 
substance  having  similar  qualities.  The  like  poles  of 
magnets  will  repel  each  other  because  of  the  obvious  im- 
possibility of  uniting  two  influences  or  forces  of  practi- 
cally equal  strength  but  flowing  in  opposite  directions. 
The  unlike  poles  of  magnets  attract  each  other  because 
the  force  is  flowing  in  the  same  direction.  The  flow  of 
magnetism  is  through  the  magnet  from  south  to  north  and 
the  circuit  is  completed  by  the  flow  of  magnetic  influence 
through  the  air  gap  or  metal  armature  bridging  it  from 
the  north  to  the  south  pole. 

FOKMS    OF    MAGNETS    AND    ZONE    OF    MAGNETIC    INFLUENCE 

DEFINED  J  4» 

Magnets  are  commonly  made  in  two  forms,  either  in 
the  shape  of  a  bar  or  horseshoe.  These  two  forms  are 
made  in  two  types,  simple  or  compound.  The  latter  are 
composed  of  a  number  of  magnets  of  the  same  form  united 
so  the  ends  of  like  polarity  are  laced  together,  and  such 
a  construction  will  be  more  efficient  and  have  more  strength 
than  a  simple  magnet  of  the  same  weight.  The  two  com- 
mon forms  of  simple  and  compound  magnets  are  shown 
at  C,  Fig.  57.  The  zone  in  which  a  magnetic  influence 
occurs  is  called  the  magnetic  field,  and  this  force  can  be 
graphically  shown  by  means  of  imaginary  lines,  which 
are  termed  "lines  of  force."  As  will  be  seen  from  the 
diagram  at  D,  Fig.  57,  the  lines  show  the  direction  of 
action  of  the  magnetic  force  and  also  show  its  strength, 
as  they  are  closer  together  and  more  numerous  when  the 
intensity  of  the  magnetic  field  is  at  its  maximum.  A 
simple  method  of  demonstrating  the  presence  of  the  force 
is  to  lay  a  piece  of  thin  paper  over  the  pole  pieces  of  either 
a  bar  or  horseshoe  magnet  and  sprinkle  fine  iron  filings 


Magnets  and  Zone  of  Influence  161 

on  it.  The  particles  of  metal  arrange  themselves  in  very 
much  the  manner  shown  in  the  illustrations  and  prove 
that  the  magnetic  field  actually  exists. 

The  form  of  magnet  used  will  materially  affect  the 
size  and  area  of  the  magnetic  field.  It  will  be  noted  that 
the  field  will  be  concentrated  to  a  greater  extent  with 
the  horseshoe  form  because  of  the  proximity  of  the  poles. 
It  should  be  understood  that  these  lines  have  no  actual 
existence,  but  are  imaginary  and  assumed  to  exist  only 
to  show  the  way  the  magnetic  field  is  distributed.  The 
magnetic  influence  is  always  greater  at  the  poles  than 
at  the  center,  and  that  is  why  a  horseshoe  or  U-form 
magnet  is  used  in  practically  all  magnetos  or  dynamos. 
This  greater  attraction  at  the  poles  can  be  clearly  dem- 
onstrated by  sprinkling  iron  filings  on  bar  and  U  mag- 
nets, as  outlined  at  E,  Fig.  57.  A  large  mass  gathers  at 
the  pole  pieces,  gradually  tapering  down  toward  the  point 
where  the  attraction  is  least. 

From  the  diagrams  it  will  be  seen  that  the  flow  of 
magnetism  is  from  one  pole  to  the  other  by  means  of 
curved  paths  between  them.  This  circuit  is  completed 
by  the  magnetism  flowing  from  one  pole  to  the  other 
through  the  magnet,  and  as  this  flow  is  continued  as  long 
as  the  body  remains  magnetic  it  constitutes  a  magnetic 
circuit.  If  this  flow  were  temporarily  interrupted  by 
means  of  a  conductor  of  electricity  moving  through  the 
field  there  would  be  a  current  of  electricity  induced  in 
the  conductor  every  time  it  cut  the  lines  of  force.  There 
are  three  kinds  of  magnetic  circuits.  A  non-magnetic 
circuit  is  one  in  which  the  magnetic  influence  completes 
its  circuit  through  some  substance  not  susceptible  to  the 
force.  A  closed  magnetic  circuit  is  one  in  which  the  in- 
fluence completes  its  circuit  through  some,  magnetic  ma- 
terial which  bridges  the  gap  between  the  poles.  A  com- 
pound circuit  is  that  in  which  the  magnetic  influence 
passes  through  magnetic  substances  and  non-magnetic  sub- 
stances in  order  to  complete  its  circuit. 


162  Aviation  Engines 


HOW    IRON    AND    STEEL    BARS    ARE    MADE    MAGNETIC 

Magnetism  may  be  produced  in  two  ways,  by  contact 
or  induction.  If  a  piece  of  steel  is  rubbed  on  a  magnet 
it  will  be  found  a  magnet  when  removed,  having  a  north 
and  south  pole  and  all  of  the  properties  found  in  the 
energizing  magnet.  This  is  magnetizing  by  contact.  A 
piece  of  steel  will  retain  the  magnetism  imparted  to  it  for 
a  considerable  length  of  time,  and  the  influence  that  re- 
mains is  known  as  residual  magnetism.  This  property 
may  be  increased  by  alloying  the  steel  with  tungsten  and 
hardening  it  before  it  is  magnetized.  Any  material  that 
will  retain  its  magnetic  influence  after  removal  from  the 
source  of  magnetism  is  known  as  a  permanent  magnet. 
If  a  piece  of  iron  or  steel  is  brought  into  the  magnetic 
field  of  a  powerful  magnet  it  becomes  a  magnet  without 
actual  contact  with  the  energizer.  This  is  magnetizing 
by  magnetic  induction.  If  a  powerful  electric  current 
flows  through  an  insulated  conductor  wound  around  a 
piece  of  iron  or  steel  it  will  make  a  magnet  of  it.  This 
is  magnetizing  by  electro-magnetic  induction.  A  magnet 
made  in  this  manner  is  termed  an  electro-magnet  and 
usually  the  metal  is  of  such  a  nature  that  it  will  not 
retain  its  magnetism  when  the  current  ceases  to  flow 
around  it.  Steel  is  used  in  all  cases  where  permanent 
magnets  are  required,  while  soft  iron  is  employed  in  all 
cases  where  an  intermittent  magnetic  action  is  desired. 
Magneto  field  magnets  are  always  made  of  tungsten  steel 
alloy,  so  treated  that  it  will  retain  its  magnetism  for 
lengthy  periods. 

ELECTRICITY  AND  MAGNETISM  CLOSELY  RELATED 

There  are  many  points  in  which  magnetism  and  elec- 
tricity are  alike.  For  instance,  air  is  a  medium  that  of- 
fers considerable  resistance  to  the  passage  of  both  mag- 
netic influence  and  electric  energy,  although  it  offers  more 
resistance  to  the  passage  of  the  latter.  Minerals  like 
iron  or  steel  are  very  easily  influenced  by  magnetism  and 


Principles  of  Magneto  Outlined  163 

easily  penetrated  by  it.  When  one  of  these  is  present 
in  the  magnetic  circuit  the  magnetism  will  flow  through 
the  metal.  Any  metal  is  a  good  conductor  for  the  pas- 
sage of  the  electric  current,  but  few  metals  are  good 
conductors  of  magnetic  energy.  A  body  of  the  proper 
metal  will  become  a  magnet  due  to  induction  if  placed 
in  the  magnetic  field,  having  a  south  pole  where  the  lines 
of  force  enter  it  and  a  north  pole  where  they  pass  out. 

We  have  seen  that  a  magnet  is  constantly  surrounded 
by  a  magnetic  field  and  that  an  electrical  conductor  when 
carrying  a  current  is  also  surrounded  by  a  field  of  mag- 
netic influence.  Now  if  the  conductor  carrying  a  current 
of  electricity  will  induce  magnetism  in  a  bar  of  iron  or 
steel,  by  a  reversal  of  this  process,  a  magnetized  iron  or 
steel  bar  will  produce  a  current  of  electricity  in  a  con- 
ductor. It  is  upon  this  principle  that  the  modern  dynamo 
or  magneto  is  constructed.  If  an  electro-motive  force  is 
induced  in  a  conductor  by  moving  it  across  a  field  of  mag- 
netic influence,  or  by  passing  a  magnetic  field  near  a 
conductor,  electricity  is  said  to  be  generated  by  magneto- 
electric  induction.  All  mechanical  generators  of  the  elec- 
tric current  using  permanent  steel  magnets  to  produce  a 
field  of  magnetic  influence  are  of  this  type*. 

BASIC    PRINCIPLES    OF    MAGNETO    OUTLINED 

The  accompanying  diagram,  Fig.  58,  will  show  these 
principles  very  clearly.  As  stated  on  an  earlier  page, 
if  the  lines  of  force  in  the  .magnetic  field  are  cut  by  a 
suitable  conductor  an  electrical  impulse  will  be  produced 
in  that  conductor.  In  this  simple  machine  the  lines  of 
force  exist  between  the  poles  of  a  horseshoe  magnet.  The 
conductor,  which  in  this  case  is  a  loop  of  copper  wire, 
is  mounted  upon  a  spindle  in  order  that  it  may  be  rotated 
in  the  magnetic  field  to  cut  the  lines  of  magnetic  influ- 
ence present  between  the  pole  pieces.  Both  of  the  ends 
of  this  loop  are  connected,  one  with  the  insulated  drum 
shown  upon  the  shaft,  the  other  to  the  shaft.  Two  metal 
brushes  are  employed  to  collect  the  current  and  cause  it 


164 


Aviation  Engines 


to  flow  through  the  external  circuit.  It  can  be  seen  that 
when  the  shaft  is  turned  in  the  direction  of  the  arrow 
the  loop  will  cut  through  the  lines  of  magnetic  influence 
and  a  current  will  be  generated  therein. 


Insulated  Ring' 
Loop  of  Wire 
Spindle 


Brushes* 


Fig.  58. — Elementary  Form  of  Magneto  Showing  Principal  Parts  Simplified 
to  Make  Method  of  Current  Generation  Clear. 

The  pressure  of  the  current  and  the  amount  produced 
vary  in  accordance  to  the  rapidity  with  which  the  lines 
of  magnetic  influence  are  cut.  The  armature  of  a  practi- 
cal magneto,  therefore,  differs  materially  from  that  shown 
in  the  diagram.  A  large  number  of  loops  of  wire  would 
be  mounted  upon  this  shaft  in  order  that  the  lines  of 
magnetic  influence  would  be  cut  a  greater  number  of  times 
in  a  given  period  and  a  core*  of  iron  used  as  a  backing 


Magneto  Operating  Principles 


165 


for  the  wire.  This  would  give  a  more  rapid  alternating 
current  and  a  higher  electro-motive  force  than  would  bo 
the  case  with  a  smaller  number  of  loops  of  wire. 

The  illustrations  at  Fig.  59  show  a  conventional  double 


Field 
Magnets 


B 


Armature 

Pole  /  Pole 

Pieces      ^J—±         Pieces 


Fig.  59. — Showing  How  Strength  of  Magnetic  Influence  and  of  the  Currents 
Induced  in  the  Windings  of  Armature  Vary  with  the  Eapidity  of 
Changes  of  riow. 


166  Aviation  Engines 

winding  armature  and  field  magnetic  of  a  practical  mag- 
neto in  part  section  and  will  serve  to  more  fully  em- 
phasize the  points  previously  made.  If  the  armature  or 
spindle  were  removed  from  between  the  pole  pieces  there 
would  exist  a  field  of  magnetic  influence  as  shown  at  Fig. 
57,  but  the  introduction  of  this  component  provides  a 
conductor  (the  iron  core)  for  the  magnetic  energy,  re- 
gardless of  its  position,  though  the  facility  with  which 
the  influence  will  be  transmitted  depends  entirely  upon 
the  position  of  the  core.  As  shown  at  A,  the  magnetic 
flow  is  through  the  main  body  in  a  straight  line,  while 
at  B,  which  position  the  armature  has  attained  after  one- 
eighth  revolution,  or  45  degrees  travel  in  the  direction 
of  the  arrow,  the  magnetism  must  pass  through  in  the 
manner  indicated.  At  C,  which  position  is  attained  every 
half  revolution,  the  magnetic  energy  abandons  the  longer 
path  through  the  body  of  the  core  for  the  shorter  passage 
offer  3d  by  the  side  pieces,  and  the  field  thrown  out  by  the 
cross  bar  disappears.  On  further  rotation  of  the  arma- 
ture, as  at  D,  the  body  of  the  core  again  becomes  ener- 
gized as  the  magnetic  influence  resumes  its  flow  through 
it.  These  changes  in  the  strength  of  the  magnetic  field 
when  distorted  by  the  armature  core,  as  well  as  the  in- 
tensity of  the  energy  existing  in  the  field,  affect  the 
windings,  and  the  electrical  energy  induced  therein  cor- 
responds in  strength  to  the  rapidity  with  which  these 
changes  in  magnetic  flow  occur.  The  most  pronounced 
changes  in  the  strength  of  the  field  will  occur  as  the  ar- 
mature passes  from  position  B  to  D,  because  the  magnetic 
field  existing  around  the  core  will  be  destroyed  and  again 
re-established. 

During  the  most  of  the  armature  rotation  the  changes 
in  strength  will  be  slight  and  the  currents  induced  in  the 
wire  correspondingly  small;  but  at  the  instant  the  core 
becomes  remagnetized,  as  the  armature  leaves  position  C, 
the  current  produced  will  be  at  its  maximum,  and  it  is  nec- 
essary to  so  time  the  rotation  of  the  armature  that  at  this 
instant  one  of  the  cylinders  is  in  condition  to  be  fired.  It 


Essential  Parts  of  a  Magneto  167 

is  imperative  that  the  armature  be  driven  in  such  relation 
to  the  crank- shaft  that  each  production  of  maximum  cur- 
rent coincides  with  the  ignition  point,  this  condition  exist- 
ing twice  during  each  revolution  of  the  armature,  or  at 
every  180  degrees  travel.  Each  position  shown  corre- 
sponds to  45  degrees  travel  of  the  armature,  or  one-eighth 
of  a  turn,  and  it  takes  just  three-eighths  revolution  to 
change  the  position  from  A  to  that  shown  at  D. 

ESSENTIAL  PARTS  OF  A  MAGNETO  AND  THEIR  FUNCTIONS 

The  magnets  which  produce  the  influence  that  in  turn 
induces  the  electrical  energy  in  the  winding  or  loops  of 
wire  on  the  armature,  and  which  may  have  any  even 
number  of  opposed  poles,  are  called  field  magnets.  The 
loops  of  wire  which  are  mounted  upon  a  suitable  drum 
and  rotate  in  the  field  of  magnetic  inflence  in  order  to 
cut  the  lines  of  force  is  called  an  armature  winding,  while 
the  core  is  the  metal  portion.  The  entire  assembly  is 
called  the  armature.  The  exposed  ends  of  the  magnets 
are  called  pole  pieces  and  the  arrangement  used  to  collect 
the  current  is  either  a  commutator  or  a  collector.  The 
stationary  pieces  which  bear  against  the  collector  or  com- 
mutator and  act  as  terminals  for  the  outside  circuit  are 
called  brushes.  These  brushes  are  often  of  copper,  or 
some  of  its  alloys,  because  copper  has  a  greater  electrical 
conductivity  than  any  other  metal. 

These  brushes  are  nearly  always  of  carbon,  which 
is  sometimes  electroplated  with  copper  to  increase  its 
electrical  conductivity,  though  cylinders  of  copper  wire 
gauze  impregnated  with  graphite  are  utilized  at  times. 
Carbon  is  used  because  it  is  not  so  liable  to  cut  the  metal 
of  the  commutator  as  might  be  the  case  if  the  contact  was 
of  the  metal  to  metal  type.  The  reason  for  this  is  that 
carbon  has  the  peculiar  property  in  that  it  materially  as- 
sists in  the  lubrication  of  the  commutator,  and  being  of 
soft,  unctuous  composition,  will  wear  and  conform  to  any 
irregularities  on  the  surface  of  the  metal  collector  rings. 

The  magneto  in  common  use  consists  of  a  number  of 


168  Aviation  Engines 

horseshoe  magnets  which  are  compound  in  form  and  at- 
tached to  suitable  cast-iron  pole  pieces  used  to  collect  and 
concentrate  the  magnetic  influence  of  the  various  magnets. 
Between  these  pole  pieces  an  armature  rotates.  This  is 
usually  shaped  like  a  shuttle,  around  which  are  wound 
coils  of  insulated  wire.  These  are  composed  of  a  large 
number  of  turns  and  the  current  produced  depends  in 
great  measure  upon  the  size  of  the  wire  and  the  number 
of  turns  per  coil.  An  armature  winding  of  large  wire  will 
deliver  a  current  of  great  amperage,  but  of  small  voltage. 
An  armature  wound  with  very  fine  wire  will  deliver  a 
current  of  high  voltage  but  of  low  amperage.  In  the 
ordinary  form  of  magneto,  such  as  used  for  ignition,  the 
current  is  alternating  in  character  and  the  break  in  the 
circuit  should  be  timed  to  occur  when  the  armature  is  at 
the  point  of  its  greatest  potential  or  pressure.  Where 
such  a  generator  is  designed  for  direct  current  production 
the  ends  of  the  winding  are  attached  to  the  segments  of 
a  commutator,  but  where  the  instrument  is  designed  to 
deliver  an  alternating  current  one  end  of  the  winding  is 
fastened  to  an  insulator  ring  on  one  end  of  the  armature 
shaft  and  the  other  end  is  grounded  on  the  frame  of  the 
machine. 

The  quantity  of  the  current  depends  upon  the  strength 
of  the  magnetic  field  and  the  number  of  lines  of  magnetic 
influence  acting  through  the  armature.  The  electro-motive 
force  varies  as  to  the  length  of  the  armature  winding  and 
the  number  of  revolutions  at  which  the  armature  is  rotated. 

THE    TRANSFORMER    SYSTEM    USES    LOW    VOLTAGE    MAGNETO 

The  magneto  in  the  various  systems  which  employ  a 
transformer  coil  is  very  similar  to  a  low-tension  genera- 
tor in  general  construction,  and  the  current  delivered  at 
the  terminals  seldom  exceeds  100  volts.  As  it  requires 
many  times  that  potential  or  pressure  to  leap  the  gap 
which  exists  between  the  points  of  the  conventional  spark 
plug,  a  separate  coil  is  placed  in  circuit  to  intensify  the 
current  to  one  of  greater  capacity.  The  essential  parts 


Transformer  Coil-Magneto  System 


169 


of  such  a  system  and  their  relation  to  each  other  are 
shown  in  diagrammatic  form  at  Fig.  60  and  as  a  com- 
plete system  at  Fig.  61.  As  is  true  of  other  systems  the 
magnetic  influence  is  produced  by  permanent  steel  mag- 
nets clamped  to  the  cast-iron  pole  pieces  between  which 
the  armature  rotates.  At  the  point  of  greatest  potential 


•Distributor  Plate 
Distributor  Arm 


•Armature 


/WWWVWVWWW-1 

Secondary  Winding  nxj[WA 


Interrupter 

Adjustment     /          \Qrounded 

Insulated       Contact 

Contact 


Fig.  60. — Diagrams  Explaining  Action  of  Low  Tension  Transformer  Coil  and 
True  High  Tension  Magneto  Ignition  Systems. 

in  the  armature  winding  the  current  is  broken  by  the 
contact  breaker,  which  is  actuated  by  a  cam,  and  a  cur- 
rent of  higher  value  is  induced  in  the  secondary  winding 
of  the  transformer  coil  when  the  low  voltage  current  is 
passed  through  the  primary  winding. 

It  will  be  noted  that  the  points  of  the  contact  breaker 
are  together  except  for  the  brief  instant  when  separated 
by  the  action  of  the  point  of  the  cam  upon  the  lever.  It 
is  obvious  that  the  armature  winding  is  short-circuited 


170 


Aviation  Engines 


Transformer  Coil-Magneto  System 


171 


upon  itself  except  when  the  contact  points  are  separated. 
While  the  armature  winding  is  thus  short-circuited  there 
will  be  practically  no  generation  of  current.  When  the 
points  are  separated  there  is  a  sudden  flow  of  current 
through  the  primary  winding  of  the  transformer  coil,  in- 
ducing a  secondary  current  in  the  other  winding,  which 
can  be  varied  in  strength  by  certain  considerations  in  the 


To  Second  Set 
Spark  Plugs 


6  Volt  Battery 


Fig.  61. — Berling  Two-Spark  Dual  Ignition  System. 

preliminary  design  of  the  apparatus.  This  current  of 
higher  potential  or  voltage  is  conducted  directly  to  the 
plug  if  the  device  is  fitted  to  a  single-cylinder  engine,  or 
to  the  distributor  arm  if  fitted  to  a  multiple-cylinder  mo- 
tor. The  distributor  consists  of  an  insulator  in  which  is 
placed  a  number  of  segments,  one  for  each  cylinder  to 
be  fired,  and  so  spaced  that  the  number  of  degrees  be- 
tween them  correspond  to  the  ignition  points  of  the  motor. 
A  two-cylinder  motor  would  have  two  segments,  a  three- 
cylinder,  three  segments,  and  so  on  within  the  capacity 
of  the  instrument.  In  the  illustration  a  four-cylinder  dis- 
tributor is  fitted,  and  the  distributing  arm  is  in  contact 


172 


.  Aviation  Engines 


with  the  segment  corresponding  to  the  cylinder  about  to 
be  fired. 

TRUE  HIGH-TENSION  MAGNETOS  ARE  SELF-CONTAINED 

The  true  high-tension  magneto  differs  from  the  pre- 
ceding inasmuch  as  the  current  of  high  voltage  is  pro- 
duced in  the  armature  winding  direct,  without  the  use  of 
the  separate  coil.  Instead  of  but  one  coil,  the  armature 
carries  two,  one  of  comparatively  coarse  wire,  the  other 
of  many  turns  of  finer  wire.  The  arrangement  of  these 


Fig.  62. — Berling  Double-Spark  Independent  System. 

windings  can  be  readily  ascertained  by  reference  to  the 
diagram  B,  Fig.  60,  which  shows  the  principle  of  opera- 
tion very  clearly.  The  simplicity  of  the  ignition  system 
is  evidently  by  inspection  of  Fig.  62.  One  end  of  the 
primary  winding  (coarse  wire)  is  coupled  or  grounded 
to 'the  armature  core,  and  the  other  passes  to  the  insu- 
lated part  of  the  interrupter.  While  in  some  forms  the 
interrupter  or  contact  breaker  mechanism  does  not  re- 
volve, the  desired  motion  being  imparted  to  the  contact 
lever  to  separate  the  points  of  a  revolving  cam,  in  this 
the  cam  or  tripping  mechanism  is  stationary  and  the  con- 
tact breaker  revolves.  This  arrangement  makes  it  pos- 
sible to  conduct  the  current  from  the  revolving  primary 
coil  to  the  interrupter  by  a  direct  connection,  eliminating 


High  Tension  Magnetos  Self -Contained         173 

the  use  of  brushes,  which  would  otherwise  be  necessary. 
In  other  forms  of  this  appliance  where  the  winding  is 
stationary,  the  interrupter  may  be  operated  by  a  revolv- 
ing cam,  though,  if  desired,  the  used  of  a  brush  at  this 
point  will  permit  this  construction  with  a  revolving 
winding. 

During  the  revolution  of  the  armature  the  grounded 
lever  makes  and  breaks  contact  with  the  insulated  point, 
short-circuiting  the  primary  winding  upon  itself  until  the 
armature  reaches  the  proper  position  of  maximum  in- 
tensity of  current  production,  at  which  time  the  circuit  is 
broken,  as  in  the  former  instance.  One  end  of  the  sec- 
ondary winding  (fine  wire)  is  grounded  on  the  live  end  of 
the  primary,  the  other  end  being  attached  to  the  revolv- 
ing arm  of  the  distributor  mechanism.  So  long  as  a  closed 
circuit  is  maintained  feeble  currents  will  pass  through  the 
primary  winding,  and  so  long  as  the  contact  points  are 
together  this  condition  will  exist.  When  the  current 
reaches  its  maximum  value,  because  of  the  armature  be- 
ing in  the  best  position,  the  cam  operates  the  interrupter 
and  the  points  are  separated,  breaking  the  short  circuit 
which  has  existed  in  the  primary  winding. 

The  secondary  circuit  has.  been  open  while  the  distrib- 
utor arm  has  moved  from  one  contact  to  another  and  there 
has  been  no  flow  of  energy  through  this  winding.  While 
the  electrical  pressure  will  rise  in  this,  even  if  the  dis- 
tributor arm  contacted  with  one  of  the  segments,  there 
would  be  no  spark  at  the  plug  until  the  contact  points 
separated,  because  the  current  in  the  secondary  winding 
would  not  be  of  sufficient  strength.  When  the  interrupter 
operates,  however,  the  maximum  primary  current  will  be 
diverted  from  its  short  circuit  and  can  flow  to  the  ground 
only  through  the  secondary  winding  and  spark-plug  cir- 
cuit. The  high  pressure  now  existing  in  the  secondary 
winding  will  be  greatly  increased  by  the  sudden  flow  of 
primary  current,  and  energy  of  high  enough  potential  to 
successfully  bridge  the  gap  at  the  plug  is  thereby  pro- 
duced in  the  winding. 


174 


Aviation  Engines 


THE  BERLING  MAGNETO 


The  Berling  magneto  is  a  true  high  tension  type  de- 
livering two  impulses  per  revolution,  but  it  is  made  in  a 
variety  of  forms,  both  single  and  double  spark.  Its  prin- 
ciple of  action  does  not  differ  in  essentials  from  the  high 


Fig.  63. — Type  DD  Berling  High  Tension  Magneto. 

tension  type  previously  described.  This  magneto  is  used 
on  Curtiss  aviation  engines  and  will  deliver  sparks  in  a 
positive  manner  sufficient  to  insure  ignition  of  engines  up 
to  200  horse-power  and  at  rotative  speeds  of  the  magneto 
armature  up  to  4,000  r.  p.  m.  which  is  sufficient  to  take 
care  of  an  eight-cylinder  V  engine  running  up  to  2,000 


Berling  Ignition  Magneto  175 

r.  p.  m.  The  magneto  is  driven  at  crank- shaft  speed  on 
four-cylinder  engines,  at  1%  times  crank- shaft  speed  on  six- 
cylinder  engines  and  at  twice  crank- shaft  speed  on  eight- 
cylinder  V  types.  The  types  "D"  and  "DD"  BER- 
LING Magnetos  are  interchangeable  with  corresponding 
magnetos  of  other  standard  makes.  The  dimensions  of 
the  four-,  six-  and  eight-cylinder  types  "D"  and  "DD" 
are  all  the  same. 

The  ideal  method  of  driving  the  magneto  is  by  means 
of  flexible  direct  connecting  coupling  to  a  shaft  intended 
for  the  purpose  of  driving  the  magneto.  As  the  magneto 
must  be  driven  at  a  high  speed,  a  coupling  of  some 
flexibility  is  preferable.  The  employment  of  such  a  coup- 
ling will  facilitate  the  mounting  of  the  magneto,  because 
a  small  inaccuracy  in  the  lining  up  of  the  magneto  with 
the  driving  shaft  will  be  taken  care  of  by  the  flexible 
coupling,  whereas  with  a  perfectly  rigid  coupling  the: 
line-up  of  the  magneto  must  be  absolutely  accurate.  An- 
other advantage  of  the  flexible  coupling  is  that  the  vibra- 
tion of  the  motor  will  not  be  as  fully  transmitted  to  the 
armature  shaft  on  the  magneto  as  in  case  a  rigid  coup- 
ling is  used.  This  means  prolonged  life  for  the  magneto. 

The  next  best  method  of  driving  the  magneto  is  by 
means  of  a  gear  keyed  to  the  armature  shaft.  When 
this  method  of  driving  is  employed,  great  care  must  be 
exercised  in  providing  sufficient  clearance  between  the 
gear  on  the  magneto  and  the  driving  gear.  If  there 
should  be  a  tight  spot  between  these  two  gears  it  will 
react  disadvantageously  on  the  magneto.  The  third 
available  method  is  to  drive  the  magneto  by  means  of 
a  chain.  This  is  the  least  desirable  of  the  three  methods 
and  should  be  resorted  to  only  in  case-  of  absolute  neces- 
sity. It  is  difficult  to  provide  sufficient  clearance  when 
using  a  chain  without  rendering  the  timing  less  accurate 
and  positive. 

Fig.  "64,  A"  shows  diagramm£tically  the  circuit  of  the 
"D"  type  two-spark  independent  magneto  and  the  switch 
used  with  it.  In  position  OFF  the  primary  winding 


176 


Aviation  Engines 


of  the  magneto  is  short-circuited  and  in  this  position 
the  switch  serves  as  an  ordinary  cut-out  or  grounding 
switch.  In  position  "1"  the  switch  connects  the  mag- 
neto in  such  a  way  that  it  operates  as  an  ordinary 
single-spark  magneto.  In  this  position  one  end  of  the 


Distributor 

Finger ^ 


^—  Primary  Circuit 

Secondary    " 

Ground  (Frame) 


C^iL-V:'      Condenser.       \    .  Interrupter 

n  fisfl  n '. 


I 

Front  View  of  Switch 


Distributor 
Finger-, 


J 

Magneto  Interrupter''    ''Battery  Timer 
B 


Back  Vi'ew 
of  Switch 


Fig.  64. — Wiring1  Diagrams  of  Berling  Magneto  Ignition  Systems. 

secondary  winding  is  grounded  to  the  body  of  the  motor. 
This  is  the  starting  position.  In  this  position  of  the 
switch  the  entire  voltage  generated  in  the  magneto  is 
concentrated  at  one  spark-plug  instead  of  being  divided 
in  half.  With  the.  motor  turning  over  very  slowly,  as  is 
the  case  in  starting,  the  full  voltage  generated  by  the 


Berling  Ignition  Magneto  177 

magneto  will  not  in  all  cases  be  sufficient  to  bridge  simul- 
taneously two  spark  gaps,  but  is  amply  sufficient  to 
bridge  one.  Also,  this  position  of  the  switch  tends  to 
retard  the  ignition  and  should  be  used  in  starting  to 
prevent  back-firing.  "With  the  switch  in  position  "2" 
the  magneto  applies  ignition  to  both  plugs  in  each 
cylinder  simultaneously.  This  is  the  normal  running 
position. 

Fig.  64,  B  shows  diagrammatically  the  circuit  of  the 
type  "DD"  BERLING  high-tension  two-spark  dual  mag- 
neto. This  type  is  recommended  for  certain  types  of 
heavy-duty  airplane  motors,  which  it  is  impossible  to  turn 
over  fast  enough  to  give  the  magneto  sufficient  speed  to 
generate  even  a  single  spark  of  volume  great  enough  to 
ignite  the  gas  in  the  cylinder.  The  dual  feature  consists 
of  .the  addition  to  the  magneto  of  a  battery  interrupter. 
The  equipment  consists  of  the  magneto,  coil  and  special 
high-tension  switch.  The  coil  is  intended  to  operate  on 
six  volts.  Either  a  storage  battery  or  dry  cells  may  be 
used. 

With  the  switch  in  the  OFF  position,  the  magneto  is 
grounded,  and  the  battery  circuit  is  open.  With  the 
switch  in  the  second  or  battery  position  marked  "BAT," 
one  end  of  the  secondary  winding  of  the  magneto  is 
grounded,  and  the  magneto  operates  as  a  single-spark 
magneto  delivering  high-tension  current  to  the  inside 
distributor,  and  the  battery  circuit  being  closed  the  high- 
tension  current  from  the  coil  is  delivered  to  the  outside 
distributor.  In  this  position  the  battery  current  is  sup- 
plied to  one  set  of  spark  plugs,  no  matter  how  slowly 
the  motor  is  turned  over,  but  as  soon  as  the  motor  starts, 
the  magneto  supplies  current  as  a  single-spark  magneto 
to  the  other  set  of  the  spark-plugs.  After  the  engine  is 
running,  the  switch  should  be  thrown  to  the  position 
marked  "MAG."  The  battery  and  coil  are  then  dis- 
connected, and  the  magneto  furnishes  ignition  to  both 
plugs  in  each  cylinder.  This  is  the  normal  running 
position.  Either  u  non-vibrating  coil  type  "N-l"  is 


178  Aviation  Engines 

furnished  or  a  combined  vibrating  and  non-vibrating  coil 
type  "VN-1." 

SETTING  BERLING  MAGNETO 

The  magneto  may  be  set  according  to  one  of  two 
different  methods,  the  selection  of  which  is,  to  some 
extent,  governed  by  the  characteristics  of  the  engine, 
but  largely  due  to  the  personal  preference  on  the  part 
of  the  user.  In  the  first  method  described  below,  the 
most  advantageous  position  of  the  piston  for  fully  ad- 
vanced ignition  is  determined  in  relation  to  the  extreme 
advanced  position  of  the  magneto.  In  this  case,  the 
fully  retarded  ignition  will  not  be  a  matter  of  selection, 
but  the  timing  range  of  the  magneto  is  wide  enough  to 
bring  the  fully  retarded  ignition  after  top-center  position 
of  the  piston.  The  second  method  for  the  setting  of  the 
magneto  fixes  the  fully  retarded  position  of  the  magneto 
in  relation  to  that  position  of  the  piston  where  fully 
retarded  ignition  is  desired.  In  this  case,  the  extreme 
advance  position  of  the  magneto  will  not  always  corre- 
spond with  the  best  position  of  the  piston  for  fully  ad- 
vanced ignition,  and  the  amount  of  advance  the  magneto 
should  have  to  meet  ideal  requirements  in  this  respect 
must  be  determined  by  experiment. 

First  Method: 

1.  Designate  one  cylinder  as  cylinder  No.  1. 

2.  Turn  the  crank-shaft  until  the  piston  in  cylinder 
No.  1  is  in  the  position  where  the  fully  advanced  spark 
is  desired  to  occur. 

3.  Eemove  the  cover  from  the  distributor  block  and 
turn  the  armature  shaft  in  the  direction  of  rotation  of  the 
magneto    until    the    distributor    finger-brush    comes    into 
such  a  position  that  this  brush  makes  contact  with  the 
segment  which  is  connected  to  the  cable  terminal  marked 
"1."     This  is   either  one   of  the  two  bottom   segments, 
depending  upon  the  direction  of  rotation. 

4.  Place    the    cam  housing   in   extreme    advance,   i.e., 


Timing  Berling  Magneto  179 

turn  the  cam  housing  until  it  stops,  in  the  direction 
opposite  to  the  direction  of  rotation  of  the  armature. 
With  the  cam  housing  in  this  position,  open  the  cover. 

5.  "With  the  armature  in  the  approximate  position  as 
described  in  "3,"  turn  the  armature   slightly  in  either 
direction  to  such  a  point  that  the  platinum  points  of  the 
magneto  interrupter  will  just  begin  to  open  at  the  end 
of  the  cam,  adjacent  to  the  fibre  lever  on  the  interrupter. 

6.  With  this  exact  position  of  the  armature,  fix  the 
magneto  to  the  driving  member  of  the  engine. 

Second  Method: 

1.  Designate  one  cylinder  as  cylinder  No.  1. 

2.  Turn  the  crank-shaft  until  the  piston  in  cylinder 
No.  1  is  in  the  position  at  which  the  fully  retarded  spark 
is  desired  to  occur. 

3.  Same  as  No.  3  under  First  Method. 

4.  Place  the  cam  housing  in  extreme  retard,  i.e.,  turn 
the  cam  housing  until  it  stops,  in  the  same  direction  as 
the  direction  of  rotation  of  the  armature.    With  the  cam 
housing  in  this  position,  open  the  cover. 

5.  Same  as  No.  5  under  First  Method. 

6.  Same  as  No.  6  under  First  Method. 

WIRING    THE    MAGNETO 

The  wiring  of  the  magneto  is  clearly  shown  by  wiring 
diagram. 

First  determine  the  sequence  of  firing  for  the  cylinders 
and  then  connect  the  cables  to  the  spark  plug  in  the 
cylinders  in  proper  sequence,  beginning  with  cylinder 
No.  1  marked  on  the  distributor  block. 

The  switch  used  with  the  independent  type  must  be 
mounted  in  such  a  manner  that  there  will  be  a  metallic 
connection  between  the  frame  of  the  magneto  and  the 
metal  portion  of  the  switch. 

It  is  advisable  to  use  a  separate  battery,  either  storage 
or  dry  cells,  as  a  source  of  current  for  the  dual  equip- 


180  Aviation  Engines 

ment.  Connecting  to  the  same  battery  that  is  used  with 
the  generator  and  other  electrical  equipment  may  cause 
trouble,  as  a  "ground"  in  this  battery  causes  the  coil 
to  overheat. 

CARE    AND    MAINTENANCE 

Lubrication: 

Use  only  the  very  best  of  oil  for  the  oil  cups. 

Put  five  drops  of  oil  in  the  oil  cup  at  the  driving  end 
of  the  magneto  for  every  fifty  hours  of  actual  running. 

Put  five  drops  of  oil  in  the  oil  cup  at  the  interrupter 
end  of  the  magneto,  located  at  one  side  of.  the  cam 
housing,  for  every  hundred  hours  of  actual  running. 

Lubricate  the  embossed  cams  in  the  cam  housing  with 
a  thin  film  of  vaseline  every  fifty  hours  of  actual  run- 
ning. Wipe  off  all  superfluous  vaseline.  Never  use  oil 
in  the  interrupter.  Do  not  lubricate  any  other  part  of 
the  interrupter. 

Adjusting  the  Interrupter: 

With  the  fibre  lever  in  the  center  of  one  of  the  em- 
bossed cams,  as  at  Fig.  65,  the  opening  between  the 
platinum  contacts  should  be  not  less  than  .016"  and  not 
more  than  .020".  The  gauge  riveted  to  the  adjusting 
wrench  should  barely  be  able  to  pass  between  the  con- 
tacts when  fully  open.  The  platinum  contacts  must  be 
smoothed  off  with  a  very  fine  file.  When  in  closed  posi- 
tion, the  platinum  contacts  should  make  contact  with 
each  other  over  their  entire  surfaces. 

When  inspecting  the  interrupter,  make  sure  that  the 
ground  brush  in  the  back  of  the  interrupter  base  is 
making  good  contact  with  the  surface  on  which  it  rubs. 

Cleaning  the  Distributor: 

The  distributor  block  cover  should  be  removed  for 
inspection  every  twenty-five  hours  of  actual  running 
and  the  carbon  deposit  from  the  distributor  finger-brush 
wiped  off  the  distributor  block  by  rubbing  with  a  rag 


Locating  Magneto  Trouble 


181 


or  piece  of  waste  dipped  in  gasoline  or  kerosene.  The 
high-tension  terminal  brush  on  the  side  of  the  magneto 
should  also  be  carefully  inspected  for  proper  tension. 


LOCATING    TKOTJBLE 


Trouble  in  the  ignition  system  is  indicated  by  the 
motor  "  missing, "  stopping  entirely,  or  by  inability  to 
start. 

It  is  safe  to  assume  that  the  trouble  is  not  in  the 


Lev er  Retaining 
5  p  ring. 


.Com 


Contact   Points 
Separated- 


Fibre 

Interrupter 
Lever 


Contact  Breaker'* 
Housing 


"----Cam 


Fig.  65. — The  Berling  Magneto  Breaker  Box  Showing  Contact  Points 
Separated  and  Interrupter  Lever  on  Cam. 

magneto,  and  the  carburetor,  gasoline  supply  and  spark- 
plugs should  first  be  investigated. 

If  the  magneto  is  suspected,  the  first  thing  to  do  is 
to  determine  if  it  will  deliver  a  spark.  To  determine 
this,  disconnect  one  of  the  high-tension  leads  from  the 
spark-plug  in  one  of  the  cylinders  and  place  it  so  that 
there  is  approximately  Vie"  between  the  terminal  and 
the  cylinder  frame. 

Open  the  pet  cocks  on  the  other  cylinders  to  prevent 
the  engine  from  firing  and  turn  over  the  engine  until 
the  piston  is  approaching  the  end  of  the  compression 


182  Aviation  Engines 

stroke  in  the  cylinder  from  which  the  cable  has  been 
removed.  Set  the  magneto  in  the  advance  position  and 
rapidly  rock  the  engine  over  the  top-center  position, 
observing  closely  if  a  spark  occurs  between  the  end  of 
the  high-tension  cable  and  the  frame. 

If  the  magneto  is  of  the  dual  type,  the  trouble  may 
be  either  in  the  magneto  or  in  the  battery  or  coil  system, 
therefore  disconnect  the  battery  and  .place  the  switch 
in  the  position  marked  "MAG."  The  magneto  will  then 
operate  as  an  independent  magneto  and  should  spark 
in  the  proper  manner.  After  this  the  battery  system 
should  be  investigated.  To  test  the  operation  of  the 
battery  and  coil,  examine  all  connections,  making  sure 
that  they  are  clean  and  tight,  and  then  with  the  switch 
in  the  "BAT,"  rock  the  piston  slowly  back  and  forth. 
If  a  type  "VN-1"  coil  is  used,  a  shower  of  sparks  should 
jump  between  the  high-tension  cable  terminal  and  the 
cylinder  frame  when  the  piston  is  in  the  correct  position 
for  firing.  If  no  spark  occurs,  remove  the  cover  from 
the  coil  and  see  that  the  vibrating  tongue  is  free.  If  a 
type  "N-l"  coil  is  used,  a  single  spark  will  occur.  The 
battery  should  furnish  six  volts  when  connected  to  the 
coil,  and  this  should  also  be  verified. 

If  the  coil  still  refuses  to  give  a  spark  and  all  con- 
nections are  correct,  the  coil  should  be  replaced  and  the 
defective  coil  returned  to  the  manufacturer. 

If  both  magneto  and  coil  give  a  spark  when  tested 
as  just  described,  the  spark-plugs  should  be  investi- 
gated. To  do  this,  disconnect  the  cables  and  remove 
the  spark-plugs.  Then  reconnect  the  cables  to  the  plugs 
and  place  them  so  that  the  frame  portions  of  the  plugs 
are  in  metallic  connection  with  the  frame  of  the  motor. 
Then  turn  over  the  motor,  thus  revolving  the  magneto 
armature,  and  see  if  a  spark  is  produced  at  the  spark 
gaps  of  the  plugs. 

The  most  common  defects  in  spark-plugs  are  breaking 
down  of  the  insulation,  fouling  due  to  carbon,  or  too  large 
or  small  a  spark  gap.  To  clean  the  plugs  a  stiff  brush 


Locating  Magneto  Trouble 


183 


and  gasoline  should  be  used.  The  spark  gap  should  be 
about  %2"  and  never  less  than  %4".  Too  small  a  gap 
may  have  been  caused  by  beads  of  metal  forming  due 
to  the  heat  of  the  spark.  Too  long  a  gap  may  have  been 
caused  by  the  points  burning  off. 

If  the  magneto  and  spark  plugs  are  in  good  condition 
and  the   engine  does  not  run   satisfactorily,   the    setting 


-Distributor 

Cover 


Contaci- 
Brectker 


Rocking  Field'' 


Fig.  66. — The  Dixie  Model  60  for  Six-Cylinder  Airplane  Engine  Ignition. 

should  be   verified  according   to   instructions   previously 
given,  and,  if  necessary,  readjusted. 

Be  careful  to  observe  that  both  the  type  "VN-1"  and 
type  "N-l"  coils  are  so  arranged  that  the  spark  occurs 
on  the  opening  of  the  contacts  of  the  timer.  As  this  is 
just  the  reverse  of  the  usual  operation,  it  should  be  care- 
fully noted  when  any  change  in  the  setting  of  the  timer 
is  made.  The  timer  on  the  dual  type  magneto  is  ad- 
justed so  that  the  battery  spark  occurs  about  5°  later 


184 


Aviation  Engines 


than  the  magneto  spark.  This  provides  an  automatic 
advance  as  soon  as  the  switch  is  thrown  to  the  magneto 
position  "MAG."  This  relative  timing  can  be  easily 
adjusted  by  removing  the  interrupter  and  shifting  the 
cam  in  the  direction  desired. 

THE    DIXIE    MAGNETO 

The  Dixie  magneto,  shown  at  Fig.  66,  operates  on  a 
different  principle  than  the  rotary  armature  type.  It  is 
used  on  the  Hall-Scott  and  other  aviation  engines.  In 


(4)    ?.    lbT.i(.    V.j    Deep  D  S.  St'd.  Thread* 


Fig.  67. — Installation  Dimensions  of  Dixie  Model  60  Magneto. 

this  magneto  the  rotating  member  consists  of  two  pieces 
of  magnetic  material  separated  by  a  non-magnetic  center 
piece.  This  member  constitutes  true  rotating  poles  for 
the  magnet  and  rotates  in  a  field  structure,  composed  of 
two  laminated  field  pieces,  riveted  between  two  non- 
magnetic rings.  The  bearings  for  the  rotating  poles  are 


Dixie  Ignition  Magneto 


185 


mounted  in  steel  plates,  which  lie  against  the  poles  of  the 
magnets.  When  the  magnet  poles  rotate,  the  magnetic 
lines  of  force  from  each  magnet  pole  are  carried  directly 


Ma  q  n  ets .> 

Rotating 
Magnet  Poles ..,__ 


.Inductor 

Drive  Shaft 


Inductor  Shaft^ 


:— --Inductors  or  Magnet  Poles 


Plates  and  Bearings 


The  rotating  element  of  the,  Dixie  magneto.  In  the  Dixie 
there  are  no  revolving  winding$,there  is  no  moving  wire 
and  the  parts  of  the  magneto  are  reduced  to  a  minimum. 


A.G.  HAGSTROMN.Y. 


Fig.  68. — The  Rotating  Elements  of  the  Dixie  Magneto. 

to  the  field  pieces  and  through  the  windings,  without 
reversal  through  the  mass  of  the  rotating  member  and 
with  only  a  single  air  gap.  There  are  no  losses  by  flux 
reversal  in  the  rotating  part,  such  as  take  place  in  other 


186  Aviation  Engines 

machines,  and  this  is  said  to  account  for  the  high  efficiency 
of  the  instrument. 

And  this  "Mason  Principle ''  involved  in  the  operation 
of  the  Dixie  is  simplified  by  a  glance  at  the  field  struc- 
ture, consisting  of  the  non-magnetic  rings,  assembled  to 
which  are  the  field  pieces  between  which  the  rotating 
poles  revolve  (see  Fig.  68).  Eotating  between  the 
limbs  of  the  magnets,  these  two  pieces  of  magnetic  mate- 
rial form  true  extensions  to  the  poles  of  the  magnets, 
and  are,  in  consequence,  always  of  the  same  polarity. 
It  will  be  seen  there  is  no  reversal  of  the  magnetism 
through  them,  and  consequently  no  eddy  current  or  hys- 
teresis losses  which  are  present  in  the  usual  rotor  or 
inductor  types.  The  simplicity  features  of  construction 
stand  out  prominently  here,  in  that  there  are  no  revolving 
windings,  a  detail  entirely  differing  from  the  orthodox 
high-tension  instrument.  This  simplicity  becomes  in- 
stantly apparent  when  it  is  found  that  the  circuit  breaker, 
instead  of  revolving  as  it  does  in  other  types,  is  stationary 
and  that  the  whole  breaker  mechanism  is  exposed  by 
simply  turning  the  cover  spring  aside  and  removing 
cover.  This  makes  inspection  and  adjustment  particu- 
larly simple,  and  the  fact  that  no  special  tool  is  neces- 
sary for  adjustment  of  the  platinum  points — an  ordinary 
small  screw-driver  is  the  whole  "kit  of  tools"  needed  in 
the  work  of  disassembling  or  assembling — is  a  feature  of 
some  value. 

With  dust-  and  water-protecting  casing  removed,  and 
one  of  the  magnets  withdrawn,  as  in  Fig.  69,  the  winding 
can  be  seen  with  its  core  resting  on  the  field  pole  pieces 
and  the  primary  lead  attached  to  its  side.  An  important 
feature  of  the  high-tension  winding  is  that  the  heads  are 
of  insulating  material,  and  there  is  not  the  tendency  for 
the  high-tension  current  to  jump  to  the  side  as  in  the 
ordinary  armature  type  magneto.  The  high-tension  cur- 
rent is  carried  to  the  distributor  by  means  of  an  insulated 
block  with  a  spindle,  at  one  end  of  which  is  a  spring 
brush  bearing  directly  on  the  winding,  thus  shortening 


Dixie  Ignition  Magneto 


187 


the  path  -of  the  high-tension  current  and  eliminating  the 
use  of  rubber  spools  and  insulating  parts.  The  moving 
parts  of  the  magneto  need  never  be  disturbed  if  the  high- 
tension  winding  is  to  be  removed.  This  winding  con- 


Distributor 
Cover „ 


Terminals, 
to  Plugs  ; 

Contact  \    \ 
Box       J 


.'•'Cover  Retaining 
Screws 


-Cover        ^  rng 

The  whole  breaker  mechanism  is  exposed  by 
simply  turning  the  cover  spring  aside  and 
removing  cover.  A  screw  driver  is  the  only 
tool  necessary  to  adjust  the  platinum  points. 


Distributor 
Drive  Gear 


Distributor  Cover 
\. 


Distributor 

Brush 

Carrier, 


Nothing  could  be  simpler  than  Dixie  con- 
struction. By  loosening  nuts  and  turning 
clamps  aside,  the  distributor  block  can  be 
removed  and  distributor  disc  lifted 
out  of  its  housing. 


Tension 
Winding 


After  removing  the  cover  the 
magnets  can  be  taken  off-exposing 
the  high  iension  winding. 


;'  Teasion 


Condenser. 


By  taking  out  four  screws  the  con- 
denser and  high  tension  winding 
can  be  readily  removed. 


AG.H»SSTROM    N.1 


Fig.  69. — Suggestions  for  Adjusting  and  Dismantling  Dixie  Magneto.  A — 
Screw  Driver  Adjusts  Contact  Points.  B — Distributor  Block  Removed. 
C — Taking  off  Magnets.  D — Showing  How  Easily  Condenser  and  High. 
Tension  Windings  are  Removed. 


stitutes  all  of  the  magneto  windings,  no  external  spark 
coil  being  necessary.  The  condenser  is  placed  directly 
above  the  winding  and  is  easily  removable  by  taking  out 
two  screws,  instead  of  being  placed  in  an  armature  where 
it  is  inaccessible  except  to  an  expert,  and  where  it  cannot 
be  replaced  except  at  the  factory  whence  it  emanated. 


188  Aviation  Engines 

CARE    OF    THE    DIXIE    MAGNETO 

The  bearings  of  the  magneto  are  provided  with  oil 
cups  and  a  few  drops  of  light  oil  every  1,000  miles  are 
sufficient.  The  breaker  lever  should  be  lubricated  every 
1,000  miles  with  a  drop  of  light  oil,  applied  with  a  tooth- 
pick. The  proper  distance  between  the  platinum  points 
when  separated  should  not  exceed  .020  or  one-fiftieth  of 
an  inch.  A  gauge  of  the  proper  size  is  attached  to  the 
screwdriver  furnished  with  the  magneto.  The  platinum 
contacts  should  be  kept  clean  and  properly  adjusted. 
Should  the  contacts  become  pitted,  a  fine  file  should  be 
used  to  smooth  them  in  order  to  permit  them  to  come 
into  perfect  contact.  The  distributor  block  should  be 
removed  occasionally  and  inspected  for  an  accumulation 
of  carbon  dust.  The  inside  of  the  distributor  block  should 
be  cleaned  with  a  cloth  moistened  with  gasoline  and 
then  wiped  dry  with  a  clean  cloth.  When  replacing  the 
block,  care  must  be  exercised  in  pushing  the  carbon  brush 
into  the  socket.  Do  not  pull  out  the  carbon  brushes  in  the 
distributor  because  you  think  there  is  not  enough  tension 
on  the  small  brass  springs.  In  order  to  obtain  the  most 
efficient  results,  the  normal  setting  of  the  spark-plug 
points  should  not  exceed  .025  of  an  inch,  and  it  is  ad- 
visable to  have  the  gap  just  right  before  a  spark-plug  is 
inserted. 

The  spark-plug  electrodes  may  be  easily  set  by  means 
of  the  gauge  attached  to  the  screwdriver.  The  setting 
of  the  spark-plug  points  is  an  important  function  ivhich 
is  usually  overlooked,  with  the  result  that  the  magneto 
is  blamed  when  it  is  not  at  fault. 

TIMING   OF   THE    DIXIE    MAGNETO 

In  order  to  obtain  the  utmost  efficiency  from  the  en- 
gine, the  magneto  must  be  correctly  timed  to  it.  This 
operation  is  usually  performed  when  the  magneto  is  fitted 
to  the  engine  at  the  factory.  The  correct  setting  may 
vary  according  to  individuality  of  the  engine,  and  some 


Timing  of  .the  Dixie  Magneto 


189 


190  Aviation  Engines 

engines  may  require  an  earlier  setting  in  order  to  obtain 
the  best  results.  However,  should  the  occasion  arise  to 
retime  the  magneto,  the  procedure  is  as  follows:  Kotate 
the  crank-shaft  of  the  engine  until  one  of  the  pistons, 
preferably  that  of  cylinder  No.  1,  is  Me  of  an  inch  ahead 
of  the  end  of  the  compression  stroke.  With  the  timing 
lever  in  full  retard  position,  the  driving  shaft  of  the 
magneto  should  be  rotated  in  the  direction  in  which  it 
will  be  driven.  The  circuit  breaker  should  be  closely 
observed  and  when  the  platinum  contact  points  are  about 
to  separate,  the  drive  gear  or  coupling  should  be  secured 
to  the  drive  shaft  of  the  magneto.  Care  should  be  taken 
not  to  alter  the  position  of  the  magneto  shaft  when 
tightening  the  nut  to  secure  the  gear  or  coupling,  after 
which  the  magneto  should  be  secured  to  its  base.  Re- 
move the  distributor  block  and  determine  which  terminal 
of  the  block  is  in  contact  with  the  carbon  brush  of  the 
distributor  finger  and  connect  with  plug  wire  leading  to 
No.  1  cylinder  to  this  terminal.  Connect  the  remaining 
plug  wires  in  turn  according  to  the  proper  sequence  of 
firing  of  the  cylinders.  (See  the  wiring  diagram  for  a 
typical  six-cylinder  engine  at  Fig.  70.)  A  terminal  on 
the  end  of  the  cover  spring  of  the  magneto  is  provided 
for  the  purpose  of  connecting  the  wire  leading  to  a  ground 
switch  for  stopping  the  engine. 

A  special  model  or  type  of  magneto  is  made  for 
V  engines  which  use  a  compound  distributor  construc- 
tion instead  of  the  simple  type  on  the  model  illustrated 
and  a  different  interior  arrangement  permits  the  pro- 
duction of  four  sparks  per  revolution  of  the  rotors.  This 
makes  it  possible  to  run  the  magneto  slower  than  would 
be  possible  with  the  two-spark  form.  The  application 
of  two  compound  distributor  magnetos  of  this  type  to  a 
Thomas-Morse  135  horse-power  motor  of  the  eight-cylin- 
der V  pattern  is  clearly  shown  at  Fig.  71. 


191 


192 


Aviation  Engines 


SPARK-PLUG    DESIGN    AND    APPLICATION 

With  the  high-tension  system  of  ignition  the  spark  is 
produced  by  a  current  of  high  voltage  jumping  between 
two  points  which  break  the  complete  circuit,  which  would 
exist  otherwise  in  the  secondary  coil  and  its  external 
connections.  The  spark-plug  is  a  simple  device  which 


Air  Starter 
\Pipe$ 


Water  Pump 


Ignition 
Cables 


Compound 
Distributor 
Magneto 


Oil  Pump 


\         Ignition 
->  r^^in 


bles 


Compound 
Distributor 
Maqneto 


Fig.  71.— How  Magneto  Ignition  is  Installed  on  Thomas-Morse  135  Horse- 
Power  Motor. 


Spark-Plug  Design  and  Application 


193 


consists  of  two  terminal  electrodes  carried  in  a  suitable 
shell  member,  which  is  screwed  into  the  cylinder.  Typical 
spark-plugs  are  shown  in  section  at  Fig.  72  and  the 
construction  can  be  easily  understood.  The  secondary 
wire  from  the  coil  is  attached  to  a  terminal  at  the  top 
of  a  central  electrode  member,  which  is  supported  in  a 
bushing  of  some  form  of  insulating  material.  The  type 
shown  at  A  employs  a  molded  porcelain  as  an  insulator, 
while  that  depicted  at  B  uses  a  bushing  of  mica.  The 


Asbestos 
Packing 


I     "I  <ff Standard 

Thread 

[  *3f Solid  Nickel  Hod 


Spark  PoMt 


Fig.  72.— Spark-Plug  Types  Showing  Construction  and  Arrangement 

of  Parts. 

insulating  bushing  and  electrode  are  housed  in  a  steel 
body,  which  is  provided  with  a  screw  thread  at  the  bot- 
tom, by  which  means  it  is  screwed  into  the  combustion 
chamber. 

When  porcelain  is  used  as  an  insulating  material  it  is 
kept  from  direct  contact  with  the  metal  portion  by  some 
form  of  yielding  packing,  usually  asbestos.  This  is  nec- 
essary because  the  steel  and  porcelain  have  different 
coefficients  of  expansion  and  some  flexibility  must  be 
provided  at  the  joints  to  permit  the  materials  to  expand 
differently  when  heated.  The  steel  body  of  the  plug  which 
is  screwed  into  the  cylinder  is  in  metallic  contact  with  it 
and  carries  sparking  points  which  form  one  of  the  ter- 
minals of  the  air  gap  over  which  the  spark  occurs.  The 


194  Aviation  Engines 

current  entering  at  the  top  of  the  plug  cannot  reach  the 
ground,  which  is  represented  by  the  metal  portion  of  the 
engine,  until  it  has  traversed  the  full  length  of  the  cen- 
tral electrode  and  overcome  the  resistance  of  the  gap 
between  it  and  the  terminal  point  on  the  shell.  The 
porcelain  bushing  is  firmly  seated  against  the  asbestos 
packing  by  means  of  a  brass  screw  gland  which  sets 
against  a  flange  formed  on  the  porcelain,  and  which 
screws  into  a  thread  at  the  upper  portion  of  the  plug 
body. 

The  mica  plug  shown  at  B  is  somewhat  simpler  in 
construction  than  that  shown  at  A.  The  mica  core  which 
keeps  the  central  electrode  separated  from  the  steel  body 
is  composed  of  several  layers  of  pure  sheet  mica  wound 
around  the  steel  rod  longitudinally,  and  hundreds  of 
stamped  steel  washers  which  are  forced  over  this  member 
and  compacted  under  high  pressure  with  some  form  of  a 
binding  material  between  them.  Porcelain  insulators  are 
usually  molded  from  high-grade  clay  and  are  approxi- 
mately of  the  shapes  desired  by  the  designers  of  the  plug. 
The  central  electrode  may  be  held  in  place  by  mechanical 
means  such  as  nuts,  packings,  and  a  shoulder  on  the  rod, 
as  shown  at  A.  Another  method  sometimes  used  is  to 
cement  the  electrode  in  place  by  means  of  some  form  of 
fire-clay  cement.  Whatever  method  of  fastening  is  used, 
it  is  imperative  that  the  joints  be  absolutely  tight  so  that 
no  gas  can  escape  at  the  time  of  explosion.  Porcelain 
is  the  material  most  widely  used  because  it  can  be  glazed 
eo  that  it  will  not  absorb  oil,  and  it  is  subjected  to  such 
high  temperature  in  baking  that  it  is  not  liable  to  crack 
when  heated. 

The  spark-plugs  may  be  screwed  into  any  convenient 
part  of  the  combustion  chamber,  the  general  practice 
being  to  install  them  in  the  caps  over  the  inlet  valves, 
or  in  the  side  of  the  combustion  chamber,  so  the  points 
will  be  directly  in  the  path  of  the  entering  fresh  gases 
from  the  carburetor. 

Other  insulating  materials  sometimes  used  are  glass, 


Spark-Plug  Design  and  Use 


195 


steatite  (which  is  a  form  of  soapstone)  and  lava.  Mica 
and  porcelain  are  the  two  common  materials  used  because 
they  give  the  best  results.  Glass  is  liable  to  crack,  while 
lava  or  the  soapstone  insulating  bushings  absorb  oil. 
The  spark  gap  of  the  average  plug  is  equal  to  about 
%2  of  an  inch  for  coil  ignition  and  %o  of  an  inch  when 
used  in  magneto  circuits.  A  simple  gauge  for  determi- 
ning the  gap  setting  is  the  thickness  of  an  ordinary  visiting 


— 23/4"  Max. 
70  mm- 


#8-32  \. 
4mm. .  7 5 p.) 


Across  Flats 

16.9  Threads  per  inch  :  1.5  millimeters  pitch 
Root  diameter  633  inch.:  16.09  millimeters 
Pitch  diameter  678*  inch  :  17.22  +02 millimeters 
Outside  diameter  7/7  inch  •  18.  2  millimeters 


Fig.  73. — Standard  Airplane  Engine  Plug  Suggested  "by  S.  A.  E.  Standards 

Committee. 

card  for  magneto  plugs,  or  a  space  equal  to  the  thickness 
of  a  worn  dime  for  a  coil  plug.  The  insulating  bushings 
are  made  in  a  number  of  different  ways,  and  while  de- 
tails of  construction  vary,  spark-plugs  do  not  differ  essen- 
tially in  design.  The  dimensions  of  the  standardized  plug 
recommended  by  the  S.  A.  E.  are  shown  at  Fig.  73. 

It  is  often  desirable  to  have  a  water-tight  joint  be- 
tween the  high-tension  cable  and  the  terminal  screw  on 
top  of  the  insulating  bushing  of  the  spark-plug,  especially 
in  marine  applications.  The  plug  shown  at  C,  Fig.  72, 


196  Aviation  Engines 

is  provided  with  an  insulating  member  or  hood  of  porce- 
lain, which  is  secured  by  a  clip  in  such  a  manner  that  it 
makes  a  water-tight  connection.  Should  the  porcelain 
of  a  conventional  form  of  plug  become  covered  with 
water  or  dirty  oil,  the  high-tension  current  is  apt  to 
run  down  this  conducting  material  on  the  porcelain  and 
reach  the  ground  without  having  to  complete  its  circuit 
by  jumping  the  air  gap  and  producing  a  spark.  It  will 
be  evident  that  wherever  a  plug  is  exposed  to  the  ele- 
ments, which  is  often  the  case  in  airplane  service,  that  it 
should  be  protected  by  an  insulating  hood  which  will  keep 
the  insulator  dry  and  prevent  short  circuiting  of  the 
spark.  The  same  end  can  be  attained  by  slipping  an 
ordinary  rubber  nipple  over  the  porcelain  insulator  of 
any  conventional  plug  and  bringing  up  one  end  over  the 
cable. 

TWO-SPARK    IGNITION 

On  most  aviation  engines,  especially  those  having  large 
cylinders,  it  is  sometimes  difficult  to  secure  complete 
combustion  by  using  a  single-spark  plug.  If  the  com- 
bustion is  not  rapid  the  efficiency  of  the  engine  will  be 
reduced  proportionately.  The  compressed  charge  in  the 
cylinder  does  not  ignite  all  at  once  or  instantaneously, 
as  many  assume,  but  it  is  the  strata  of  gas  nearest  the 
plug  which  is.  ignited  first.  This  in  turn  sets  fire  to 
consecutive  layers  of  the  charge  until  the  entire  mass 
is  aflame.  One  may  compare  the  combustion  of  gas  in 
the  gas-engine  cylinder  to  the  phenomenon  which  obtains 
when  a  heavy  object  is  thrown  into  a  pool  of  still  water. 
First  a  small  circle  is  seen  at  the  point  where  the  object 
has  passed  into  the  water,  this  circle  in  turn  inducing 
other  and  larger  circles  until  the  whole  surface  of  the 
pool  has  been  agitated  from  the  .one  central  point.  The 
method  of  igniting  the  gas  is  very  similar,  as  the  spark 
ignites  the  circle  of  gas  immediately  adjacent  to  the 
sparking  point,  and  this  circle  in  turn  ignites  a  little 
larger  one  concentric  with  it.  The  second  circle  of  flame 


Two- Spark  Ignition  197 

sets  fire  to  more  of  the  gas,  and  finally  the  entire  con- 
tents of  the  combustion  chamber  are  burning. 

While  ordinarily  combustion  is  sufficiently  rapid  with 
a  single  plug  so  that  the  proper  explosion  is  obtained  at 
moderate  engine  speeds,  if  the  engine  is  working  fast  and 
the  cylinders  are  of  large  capacity  more  power  may  be 
obtained  by  setting  fire  to  the  mixture  at  two  different 
points  instead  of  but  one.  This  may  be  accomplished  by 
using  two  sparking-plugs  in  the  cylinder  instead  of  one, 
and  experiments  have  shown  that  it  is  possible  to  gain 
from  twenty-five  to  thirty  per  cent,  in  motor  power  at 
high  speed  with  two-spark  plugs,  because  the  combustion 
of  gas  is  accelerated  by  igniting  the  gas  simultaneously 
in  two  places.  The  double-plug  system  on  airplane  en- 
gines is  also  a  safeguard,  as  in  event  of  failure  of  one 
plug  in  the  cylinder  the  other  would  continue  to  fire  the 
gas,  and  the  engine  will  continue  to  function  properly. 

In  using  magneto  ignition  some  precautions  are  neces- 
sary relating  to  wiring  and  also  the  character  of  the  spark- 
plugs employed.  The  conductor  should  be  of  good  quality, 
have  ample  insulation,  and  be  well  protected  from  accu- 
mulations of  oil,  which  would  tend  to  decompose  rubber 
insulation.  It  is  customary  to  protect  the  wiring  by  run- 
ning it  through  the  conduits  of  fiber  or  metal  tubing  lined 
with  insulating  material.  Multiple  strand  cables  should 
be  used  for  both  primary  and  secondary  wiring,  and  the 
insulation  should  be  of  rubber  at  least  %6  inch  thick. 

The  spark-plugs  commonly  used  for  battery  and  coil 
ignition  cannot  always  be  employed  when  a  magneto  is 
fitted.  The  current  produced  by  the  mechanical  generator 
has  a  greater  amperage  and  more  heat  value  than  that 
obtained  from  transformer  coils  excited  by  battery  cur- 
rent. The  greater  heat  may  burn  or  fuse  the  slender 
points  used  on  some  battery  plugs  and  heavier  electrodes 
are  needed  to  resist  the  heating  effect  of  the  more  intense 
arc.  While  the  current  has  greater  amperage  it  is  not  of 
as  high  potential  or  voltage  as  that  commonly  produced 
by  the  secondary  winding  of  an  induction  coil,  and  it 


198 


Aviation  Engines 


cannot  overcome  as  much  of  a  gap.  Manufacturers  of 
magneto  plugs  usually  set  the  spark  points  about  %4  of 
an  inch  apart.  The  most  efficient  magneto  plug  has  a 
plurality  of  points  so  that  when  the  distance  between  one 
set  becomes  too  great  the  spark  will  take  place  between 


p.—. 


Fig.  74. — Special  Mica  Plug  for  Aviation  Engines. 

one  of  the  other  pairs  of  electrodes  which  are  not  sep- 
arated by  so  great  an  air  space. 

SPECIAL  PLUGS   FOR  AIRPLANE   WORK 

Airplane  work  calls  for  special  construction  of  spark- 
plugs, owing  to  the  high  compression  used  in  the  engines 
and  the  fact  that  they  are  operated  on  open  throttle  prac- 
tically all  the  time,  thus  causing  a  great  deal  of  heat  to 


Special  Airplane  Engine  Plugs  199 

be  developed.  The  plug  shown  at  Fig.  74  was  recently 
described  in  "The  Automobile,"  and  has  been  devised 
especially  for  airplane  engines  and  automobile  racing 
power  plants.  The  core  C  is  built  up  of  mica  washers, 
and  has  square  shoulders.  As  mica  washers  of  different 
sizes  may  be  used,  and  accurate  machining,  such  as  is  nec- 
essary with  conical  clamping  surfaces,  is  not  required, 
the  plug  can  be  produced  economically.  The  square 
shoulders  of  the  core  afford  two  gasket  seats,  and  when 
the  core  is  clamped  in  the  shell  by  means  of  check  nut  E, 
it  is  accurately  centered  and  a  tight  joint  is  formed.  This 
construction  also  makes  a  shorter  plug  than  where  coni- 
cal fits  are  used,  thus  improving  the  heat  radiation  through 
the  stem.  The  lower  end  of  the  shell  is  provided  with  a 
baffle  plate  0,  which  tends  to  keep  the  oil  away  from  the 
mica.  There  are  perforations  L  in  this  baffle  plate  to 
prevent  burnt  gases  being  pocketed  behind  the  baffle  plate 
and  pre-igniting  the  new  charge.  This  construction  also 
brings  the  firing  point  out  into  the  firing  chamber  of  the 
engine,  and  has  all  the  other  advantages  of  a  closed-end 
plug.  The  stem  P  is  made  of  brass  or  copper,  on  account 
of  their  superior  heat  conductivity,  and  the  electrode  J 
is  swedged  into  the  bottom  of  the  stem,  as  shown  at  K, 
in  a  secure  manner. 

The  shell  is  finned,  as  shown  at  G,  to  provide  greater 
heat  radiating  surface.  There  is  also  a  fin  F  at  the  top 
of  the  stem,  to  increase  the  radiation  of  heat  from  the 
stem  and  electrode.  The  top  of  this  finned  portion  is 
slightly  countersunk,  and  the  stem  is  riveted  into  same, 
thereby  reducing  the  possibility  of  leakage  past  the 
threads  on  the  stem.  This  finned  portion  is  necked  at  A 
to  take  a  slip  terminal. 

In  building  up  the  core  a  small  section  of  washers,  I, 
is  built  up  before  the  mica  insulating  tube  D  is  placed  on. 
This  construction  gives  a  better  support  to  section  L 
Baffle  plate  0  is  bored  out  to  allow  the  electrode  J  to 
pass  through,  and  the  clearance  between  baffle  plate  and 
electrode  is  made  larger  than  the  width  of  the  gap  be- 


200  Aviation  Engines 

tween  the  firing  points,  so  that  there  is  no  danger  of  the 
spark  jumping  from  the  electrode  to  the  baffle  plate. 

This  plug  will  be  furnished  either  with  or  without  the 
finned  portion,  to  meet  individual  requirements.  The 
manufacturers  lay  special  stress  upon  the  simplicity  of 
construction  and  upon  the  method  of  clamping,  which  is 
claimed  to  make  the  plug  absolutely  gas-tight. 


CHAPTER   VII 

Why  Lubrication  Is  Necessary — Friction  Defined — Theory  of  Lubrica- 
tion— Derivation  of  Lubricants — Properties  of  Cylinder  Oils — 
Factors  Influencing  Lubrication  System  Selection — Gnome  Type 
Engines  Use  Castor  Oil — Hall-Scott  Lubrication  System — Oil  Sup- 
ply by  Constant  Level  Splash  System — Dry  Crank-Case  System  Best 
for  Airplane  Engines — Why  Cooling  Systems  Are  Necessary — 
Cooling  Systems  Generally  Applied — Cooling  by  Positive  Pump 
Circulation — Thermo-Syphon  System — Direct  Air-Cooling  Methods 
— Air-Cooled  Engine  Design  Considerations. 

WHY  LUBRICATION   IS   NECESSARY 

THE  importance  of  minimizing  friction  at  the  various 
bearing  surfaces  of  machines  to  secure  mechanical  effi- 
ciency is  fully  recognized  by  all  mechanics,  and  proper 
lubricity  of  all  parts  of  the  mechanism  is  a  very  essential 
factor  upon  which  the  durability  and  successful  operation 
of  the  motor  car  power  plant  depends.  All  of  the  moving 
members  of  the  engine  which  are  in  contact  with  other 
portions,  whether  the  motion  is  continuous  or  intermit- 
tent, of  high  or  low  velocity,  or  of  rectilinear  or  continued 
rotary  nature,  should  be  provided  with  an  adequate  sup- 
ply of  oil.  No  other  assemblage  of  mechanism  is  operated 
under  conditions  which  are  so  much  to  its  disadvantage 
as  the  motor  car,  and  the  tendency  is  toward  a  simplifica- 
tion of  oiling  methods  so  that  the  supply  will  be  ample 
and  automatically  applied  to  the  points  needing  it. 

In  all  machinery  in  motion  the  members  which  are  in 
contact  have  a  tendency  to  stick  to  each  other,  and  the 
very  minute  projections  which  exist  on  even  the  smooth- 
est of  surfaces  would  have  a  tendency  to  cling  or  adhere ' 
to  each  other  if  the  surfaces  were  not  kept  apart  by  some 
elastic  and  unctuous  substance.  This  will  flow  or  spread 
out  over  the  surfaces  and  smooth  out  the  inequalities 

201 


202  Aviation  Engines 

ing  which  tend  to  produce  heat  and  retard  motion  of  the 
pieces  relative  to  each  other. 

A  general  impression  which  obtains  is  that  well  ma- 
chined surfaces  are  smooth,  but  while  they  are  apparently 
free  from  roughness,  and  no  projections  are  visible  to  the 
naked  eye,  any  smooth  bearing  surface,  even  if  very  care- 
fully ground,  will  have  a  rough  appearance  if  examined 
with  a  magnifying  glass.  An  exaggerated  condition  to 
illustrate  this  point  is  shown  at  Fig.  75.  The  amount  of 
friction  will  vary  in  proportion  to  the  pressure  on  the 
surfaces  in  contact  and  will  augment  as  the  loads  in- 
crease; the  rougher  surfaces  will  have  more  friction  than 
smoother  ones  and  soft  bodies  will  produce  more  friction 
than  hard  substances. 

FRICTION  DEFINED 

Friction  is  always  present  in  any  mechanism  as  a  re- 
sisting force  that  tends  to  retard  motion  and  bring  all 
moving  parts  to  a  state  of  rest.  The  absorption  of  power 
by  friction  may  be  gauged  by  the  amount  of  heat  which 
exists  at  the  bearing  points.  Friction  of  solids  may  be 
divided  into  two  classes:  sliding  friction,  such  as  exists 
between  the  piston  and  cylinder,  or  the  bearings  of  a 
gas-engine,  and  rolling  friction,  which  is  that  present 
when  the  load  is  supported  by  ball  or  roller  bearings,  or 
that  which  exists  between  the  tires  or  the  driving  wheels 
and  the  road.  Engineers  endeavor  to  keep  friction  losses 
as  low  as  possible,  and  much  care  is  taken  in  all  modern 
airplane  engines  to  provide  adequate  methods  of  lubrica- 
tion, or  anti-friction  bearings  at  all  points  where  con- 
siderable friction  exists. 

THEORY    OF    LUBRICATION 

The  reason  a  lubricant  is  supplied  to  bearing  points 
will  be  easily  understood  if  one  considers  that  these 
elastic  substances  flow  between  the  close  fitting  surfaces, 
and  fcy  filling  up  the  minute  depressions  in  the  surfaces 
and  covering  the  high  spots  act  as  a  cushion  which 


Theory  of  Lubrication 


203 


absorbs  the  heat  generated  and  takes  the  wear  instead 
of  the  metallic  bearing  surface.  The  closer  the  parts  fit 
together  the  more  fluid  the  lubricant  must  be  to  pass 
between  their  surfaces,  and  at  the  same  time  it  must 
possess  sufficient  body  so  that  it  will  not  be  entirely 
forced  out  by  the  pressure  existing  between  the  parts. 

Oils  should  have  good  adhesive,  as  well  as  cohesive, 
qualities.     The  former  are  necessary  so  that  the  oil  film 


Pillow  Block 


Magnified 
Shaft 


Magnifying  Glass 


Fig.  75. — Showing  Use  of  Magnifying  Glass  to  Demonstrate  that  Apparently 
Smooth  Metal  Surfaces  May  Have  Minute  Irregularities  which  Produce 
Friction. 

will  cling  well  to  the  surfaces  of  the  bearings;  the  latter, 
so  the  oil  particles  will  cling  together  and  resist  the  ten- 
dency to  separation  which  exists  all  the  time  the  bearings 
are  in  operation.  When  used  for  gas-engine  lubrication 
the  oil  should  be  capable  of  withstanding  considerable 
heat  in  order  that  it  will  not  be  vaporized  by  the  hot  por- 
tions of  the  cylinder.  It  should  have  sufficient  cold  test 
so  that  it  will  remain  fluid  and  flow  readily  at  low  tem- 
perature. Lubricants  should  be  free  from  acid,  or  alka- 


204  Aviation  Engines 

lies,  which  tend  to  produce  a  chemical  action  with  metals 
and  result  in  corrosion  of  the  parts  to  which  they  are 
applied.  It  is  imperative  that  the  oil  be  exactly  the 
proper  quality  and  nature  for  the'  purpose  intended  and 
that  it  be  applied  in  a  positive  manner.  The  requirements 
may  be  briefly  summarized  as  follows : 

First — It  must  have  sufficient  body  to  prevent  seizing 
of  the  parts v  to  which  it  is  applied  and  between  which  it 
is  depended  upon  to  maintain  an  elastic  film,  and  yet  it 
must  not  have  too  much  viscosity,  in  order  to  minimize 
the  internal  or  fluid  friction  which  exists  between  the 
particles  of  the  lubricant  itself. 

Second — The  lubricant  must  not  coagulate  or  gum; 
must  not  injure  the  parts  to  which  it  is  applied,  either  by 
chemical  action  or  by  producing  injurious  deposits,  and 
it  should  not  evaporate  readily. 

Third — The  character  of  the  work  will  demand  that 
the  oil  should  not  vaporize  when  heated  or  thicken  to  such 
a  point  that  it  will  not  flow  readily  when  cold. 

Fourth — The  oil  must  be  free  from  acid,  alkalies,  ani- 
mal or  vegetable  fillers,  or  other  injurious  agencies. 

Fifth — It  must  be  carefully  selected  for  the  work  re- 
quired and  should  be  a  good  conductor  of  heat. 

DERIVATION    OF    LUBRICANTS 

The  first  oils  which  were  used  for  lubricating  machin- 
ery were  obtained  from  animal  and  vegetable  sources, 
though  at  the  present  time  most  unguents  are  of  mineral 
derivation.  Lubricants  may  exist  as  fluids,  semifluids,  or 
solids.  The  viscosity  will  vary  from  light  spindle  or 
dynamo  oils,  which  have  but  little  more  body  than  kero- 
sene, to  the  heaviest  greases  and  tallows.  The  most  com- 
mon solid  employed  as  a  lubricant  is  graphite,  sometimes 
termed  " plumbago"  or  " black  lead."  This  substance  is 
of  mineral  derivation. 

The  disadvantage  of  oils  of  organic  origin,  such  as 
those  obtained  from  animal  fats  or  vegetable  substances, 
is  that  they  will  absorb  oxygen  from  the  atmosphere, 


Derivation  of  Lubricants  205 

which  causes  them  to  thicken  or  become  rancid.  Such 
oils  have  a  very  poor  cold  test,  as  they  solidify  at  com- 
paratively high  temperatures,  and  their  flashing  point  is 
so  low  that  they  cannot  be  used  at  points  where  much 
heat  exists.  In  most  animal  oils  various  acids  are  present 
in  greater  or  less  quantities,  and  for  this  reason  they  are 
not  well  adapted  for  lubricating  metallic  surfaces  which 
may  be  raised  high  enough  in  temperature  to  cause  de- 
composition of  the  oils. 

Lubricants  derived  from  the  crude  petroleum  are 
called  ' '  Oleonaphthas ' '  and  they  are  a  product  of  the 
process  of  refining  petroleum  through  which  gasoline  and 
kerosene  are  obtained.  They  are  of  lower  cost  than  vege- 
table or  animal  oil,  and  as  they  are  of  non-organic  origin, 
they  do  not  become  rancid  or  gummy  by  constant  expo- 
sure to  the  air,  and  they  will  have  no  corrosive  action 
on  metals  because  they  contain  no  deleterious  substances 
in  chemical  composition.  By  the  process  of  fractional 
distillation  mineral  oils  of  all  grades  can  be  obtained. 
They  have  a  lower  cold  and  higher  flash  test  and  there 
is  not  the  liability  of  spontaneous  combustion  that  exists 
with  animal  oils. 

The  organic  oils  are  derived  from  fatty  substances, 
which  are  present  in  the  bodies  of  all  animals  and  in 
some  portions  of  plants.  The  general  method  of  extract- 
ing oil  from  animal  bodies  is  by  a  rendering  process, 
which  consists  of  applying  sufficient  heat  to  liquefy  the 
oil  and  then  separating  it  from  the  tissue  with  which  it 
is  combined  by  compression.  The  only  oil  which  is  used 
to  any  extent  in  gas-engine  lubrication  that  is  not  of 
mineral  derivation  is  castor  oil.  This  substance  has  been 
used  on  high-speed  racing  automobile  engines  and  on 
airplane  power  plants.  It  is  obtained  from  the  seeds  of 
the  castor  plant,  which  contain  a  large  percentage  of  oil. 

Among  the  solid  substances  which  may  be  used  for 
lubricating  purposes  may  be  mentioned  tallow,  which  is 
obtained  from  the  fat  of  animals,  and  graphite  and  soap- 
stone,  which  are  of  mineral  derivation.  Tallow  is  never 


206  Aviation  Engines 

used  at  points  where  it  will  be  exposed  to  much  heat, 
though  it  is  often  employed  as  a  filler  for  greases  used 
in  transmission  gearing  of  autos.  Graphite  is  sometimes 
mixed  with  oil  and  applied  to  cylinder  lubrication,  though 
it  is  most  often  used  in  connection  with  greases  in  the 
landing  gear  parts  and  for  coating  wires  and  cables  of 
the  airplane.  Graphite  is  not  affected  by  heat,  cold,  acids, 
or  alkalies,  and  has  a  strong  attraction  for  metal  surfaces. 
It  mixes  readily  with  oils  and  greases  and  increases  their 
efficiency  in  many  applications.  It  is  sometimes  used 
where  it  would  not  be  possible  to  use  other  lubricants 
because  of  extremes  of  temperature. 

The  oils  used  for  cylinder  lubrication  are  obtained 
almost  exclusively  from  crude  petroleum  derived  from 
American  wells.  Special  care  must  be  taken  in  the  selec- 
tion of  crude  material,  as  every  variety  will  not  yield  oil 
of  the  proper  quality  to  be  used  as  a  cylinder  lubricant. 
The  crude  petroleum  is  distilled  as  rapidly  as  possible 
with  fire  heat  to  vaporize  off  the  naphthas  and  the  burn- 
ing oils.  After  these  vapors  have  been  given  off  super- 
heated steam  is  provided  to  assist  in  distilling.  When 
enough  of  the  light  elements  have  been  eliminated  the 
residue  is  drawn  off,  passed  through  a  strainer  to  free 
it  from  grit  and  earthy  matters,  and  is  afterwards  cooled 
to  separate  the  wax  from  it.  This  is  the  dark  cylinder  oil 
and  is  the  grade  usually  used  for  steam-engine  cylinders. 

PROPERTIES   OF    CYLINDER   OILS 

The  oil  that  is  to  be  used  in  the  gasoline  engine  must 
be  of  high  quality,  and  for  that  reason  the  best  grades 
are  distilled  in  a  vacuum  that  the  light  distillates  may  be 
separated  at  much  lower  temperatures  than  ordinary 
conditions  of  distilling  permit.  If  the  degree  of  heat 
is  not  high  the  product  is  not  so  apt  to  decompose  and 
deposit  carbon.  If  it  is  desired 'to  remove  the  color  of 
the  oil  which  is  caused  by  free  carbon  and  other  impurities 
it  can  be  accomplished  by  filtering  the  oil  through  char- 
coal. The  greater  the  number  of  times  the  oil  is  filtered, 


Properties  of 'Cylinder  Oils  207 

the  lighter  it  will  become  in  color.  The  best  cylinder 
oils  have  flash  points  usually  in  excess  of  500  degrees  F., 
and  while  they  have  a  high  degree  of  viscosity  at  100 
degrees  F.  they  become  more  fluid  as  the  temperature 
increases. 

The  lubricating  oils  obtained  by  refining  crude  petro- 
leum may  be  divided  into  three  classes: 

First — The  natural  oils  of  great  body  which  are  pre- 
pared for  use  by  allowing  the  crude  material  to  settle 
in  tanks  at  high  temperature  and  from  which  the  im- 
purities are  removed  by  natural  filtration.  These  oils  are 
given  the  necessary  body  and  are  free  from  the  volatile 
substances  they  contain  by  means  of  superheated  steam 
which  provides  a  source  of  heat. 

Second — Another  grade  of  these  natural  oils  which  are 
filtered  again  at  high  temperatures  and  under  pressure 
through  beds  of  animal  charcoal  to  improve  their  color. 

Third — Pale,  limpid  oils,  obtained  by  distillation  and 
subsequent  chemical  treatment  from  the  residuum  pro- 
duced in  refining  petroleum  to  obtain  the  fuel  oils. 

Authorities  agree  that  any  form  of  mixed  oil  in  which 
animal  and  mineral  lubricants  are  combined  should  never 
be  used  in  the  cylinder  of  a  gas  engine  as  the  admixture 
of  the  lubricants  does  not  prevent  the  decomposition  of 
the  organic  oil  into  the  glycerides  and  fatty  acids  peculiar 
to  the  fat  used.  In  a  gas-engine  cylinder  the  flame  tends 
to  produce  more  or  less  charring.  The  deposits  of  carbon 
will  be  much  greater  with  animal  oils  than  with  those 
derived  from  the  petroleum  base  because  the  constituents 
of  a  fat  or  tallow  are  not  of  the  same  volatile  character 
as  those  which  comprise  the  hydro-carbon  oils  which  will 
evaporate  or  volatilize  before  they  char  in  most  instances. 

FACTORS   INFLUENCING  LUBRICATION    SYSTEM    SELECTION 

The  suitability  of  oil  for  the  proper  and  efficient  lubri- 
cation of  all  internal  combustion  engines  is  determined 
chiefly  by  the  following  factors: 


208  Aviation  Engines 

1.  Type  of  cooling  system   (operating  temperatures). 

2.  Type   of  lubricating   system    (method   of   applying 
oil  to  the  moving  parts). 

3.  Eubbing  speeds  of  contact  surfaces. 

Were  the  operating  temperatures,  bearing  surface 
speeds  and  lubrication  systems  identical,  a  single  oil 
could  be  used  in  all  engines  with  equal  satisfaction.  The 
only  change  then  necessary  in  viscosity  would  be  that  due 
to  climatic  conditions.  .As  engines  are  now  designed,  only 
three  grades  of  oil  are  necessary  for  the  lubrication  of 
all  types  with  the  exception  of  Knight,  air-cooled  and 
some  engines  which  run  continuously  at  full  load.  In  the 
specification  of  engine  lubricants  the  feature  of  load 
carried  by  the  engine  should  be  carefully  considered. 

Full  Load  Engines. 

1.  Marine. 

2.  Kacing  automobile. 

3.  Aviation. 

4.  Farm  tractor. 

5.  Some  stationary. 

Variable  Load  Engines. 

1.  Pleasure  automobile. 

2.  Commercial  vehicle. 

3.  Motor  cycle. 

4.  Some  stationary. 

Of  the  forms  outlined,  the  only  one  we  have  any 
immediate  concern  about  is  the  airplane  power  plant. 
The  Platt  &  Washburn  Kenning  Company,  who  have 
made  a  careful  study  of  the  lubrication  problem  as  ap- 
plied to  'all  types  of  engines,  have  found  a  peculiar  set 
of  conditions  to  apply  to  oiling  high-speed  constant-duty 
or  "full-load"  engines.  Modern  airplane  engines  are 
designed  to  operate  continuously  at  a  fairly  uniform 
high  rotative  speed  and  at  full  load  over  long  periods 
of  time.  As  a  sequence  to  this  heavy  duty  the  operating 


Lubricating  Airplane  Engines  209 

temperatures  are  elevated.  For  the  sake  of  extreme  light- 
ness in  weight  of  all  parts,  very  thin  alloy  steel  aluminum 
or  cast  iron  pistons  are  fitted  and  the  temperature  of 
the  thin  piston  heads  at  the  center  reaches  anywhere 
between  600°  and  1,400°  Fahr.,  as  in  automobile  racing 
engines.  Freely  exposed  to  such  intense  heat  hydro-carbon 
oils  are  partially  "cracked"  into  light  and  heavy  prod- 
ucts or  polymerized  into  solid  hydro-carbons.  From  these 
facts  it  follows  that  only  heavy  mineral  oils  of  low  carbon 
residue  and  of  the  greatest  chemical  purity  and  stability 
should  be  used  to  secure  good  lubrication.  In  all  cases 
the  oil  should  be  sufficiently  heavy  to  assure  the  highest 
horse-power  and  fuel  and  oil  economy  compatible  with 
perfect  lubrication,  avoiding,  at  the  same  time,  carbon- 
ization and  ignition  failure.  When  aluminum  pistons  are 
used  their  superior  heat-conducting  properties  aid  mate- 
rially in  reducing  the  rate  of  oil  destruction. 

The  extraordinary  evolutions  described  by  airplanes 
in  flight  make  it  a  matter  of  vital  necessity  to  operate 
engines  inclined  at  all  angles  to  the  vertical  as  well  as  in 
an  upside-down  position.  To  meet  this  situation  lubri- 
cating systems  have  been  elaborated  so  as  to  deliver 
an  abundance  of  oil  where  needed  and  to  eliminate  pos- 
sible flooding  of  cylinders.'  This  is  done  by  applying  a 
full  force  feed  system,  distributing  oil  under  considerable 
pressure  to  all  working  parts.  Discharged  through  the 
bearings,  the  oil  drains  down  to  the  suction  side  of  a 
second  pump  located  in  the  bottom  of  the  base  chamber. 
This  pump  being  of  greater  capacity  than  the  first  pre- 
vents the  accumulation  of  oil  in  the  crank-case,  and 
forces  it  to  a  separate  oil  reservoir-cooler,  whence  it 
flows  back  in  rapid  circulation  to  the  pump  feeding  the 
bearings.  With  this  arrangement  positive  lubrication 
is  entirely  independent  of  engine  position.  The  lubri- 
cating system  of  the  Thomas-Morse  aviation  engines, 
which  is  shown  at  Fig.  76,  is  typical  of  current  practice. 


hi 

PH 


210 


Gnome  Type  Engines  Use  Castor  Oil          211 


GNOME    TYPE    ENGINES    USE    CASTOR    OIL 

The  construction  and  operation  of  rotative  radial 
cylinder  engines  introduce  additional  difficulties  of  lubri- 
cation to  those  already  referred  to  and  merit  especial 
attention.  Owing  to  the  peculiar  alimentation  systems 
of  Gnome  type  engines,  atomized  gasoline  mixed  with 
air  is  drawn  through  the  hollow  stationary  crank-shaft 
directly  into  the  crank-case  which  it  fills  on  the  way  to 
the  cylinders.  Therein  lies  the  trouble.  Hydrocarbon 
oils  are  soon  dissolved  by  the  gasoline  and  washed  off, 
leaving  the  bearing  surfaces  without  adequate  protection 
and  exposed  to  instant  wear  and  destruction.  So  castor 
oil  is  resorted  to  as  an  indispensable  but  unfortunate 
compromise.  Of  vegetable  origin,  it  leaves  a  much  more 
bulky  carbon  deposit  in  the  explosion  chambers  than 
does  mineral  oil  and  its  great  affinity  for  oxygen  causes 
the  formation  of  voluminous  gummy  deposit  in  the  crank- 
case.  Engines  employing  it  need  to  be  dismounted  and 
thoroughly  scraped  out  at  frequent  intervals.  It  is  ad- 
visable to  use  only  unblended  chemically  pure  castor  oil 
in  rotative  engines,  first  by  virtue  of  its  insolubility  in 
gasoline  and  second  because  its  extra  heavy  body  can 
resist  the  high  temperature  of  air-cooled  cylinders. 

HALL-SCOTT    LUBRICATION    SYSTEM 

The  oiling  system  of  the  Hall-Scott'  type  A-5  125 
horse-power  engine  is  clearly  shown  at  Fig.  77.  It  is 
completely  described  in  the  instruction  book  issued  by 
the  company  from  which  the  following  extracts  are  repro- 
duced by  permission.  Crank-shaft,  connecting  rods  and 
all  other  parts  within  the  crank-case  and  cylinders  are 
lubricated  directly  or  indirectly  by  a  force-feed  oiling 
system.  The  cylinder  walls  and  wrist  pins  are  lubricated 
by  oil  spray  thrown  from  the  lower  end  of  connecting 
rod  bearings.  This  system  is  used  only  upon  A-5  engines. 
Upon  A-7a  and  A-5a  engines  a  small  tube  supplies  oil 


llflil 


212 


Hall- Scott  Lubricating  System  213 

from  connecting  rod  bearing  directly  upon  the  wrist  pin. 
The  oil  is  drawn  from  the  strainer  located  at  the  lowest 
portion  of  the  lower  crank-case,  forced  around  the  main 
intake  manifold  oil  jacket.  From  here  it  is  circulated 
to  the  main  distributing  pipe  located  along  the  lower  left 
hand  side  of  upper  crank-case.  The  oil  is  then  forced 
directly  to  the  lower  side  of  crank- shaft,  through  holes 
drilled  in  each  main  bearing  cup.  Leakage  from  these 
main  bearings  is  caught  in  scuppers  placed  upon  the 
cheeks  of  the  crank-shafts  furnishing  oil  under  pressure 
to  the  connecting  rod  bearings.  A-7a  and  A-5a  engines 
have  small  tubes  leading  from  these  bearings  which  con- 
vey the  oil  under  pressure  to  the  wrist  pins. 

A  bi-pass  located  at  the  front  end  of  the  distributing 
oil  pipe  can  be  regulated  to  lessen  or  raise  the  pressure. 
By  screwing  the  valve  in,  the  pressure  will  raise  and 
more  oil  will  be  forced  to  the  bearings.  By  unscrewing, 
pressure  is  reduced  and  less  oil  is  fed.  -A-7a  and  A-5a 
engines  have  oil  relief  valves  located  just  off  of  the  main 
oil  pump  in  the  lower  crank-case.  This  regulates  the 
pressure  at  all  times  so  that  in  cold  weather  there  will 
be  no  danger  of  bursting  oil  pipes  due  to  excessive  pres- 
sure. If  it  is  found  the  oil  pressure  is  not  maintained 
at  a  high  enough  level,  inspect  this  valve.  A  stronger 
spring  will  not  allow  the  oil  to  bi-pass  so  freely,  and 
consequently  the  pressure  will  be  raised;  a  weaker  spring 
will  bi-pass  more  oil  and  reduce  the  oil  pressure  mate- 
rially. Independent  of  the  above-mentioned  system,  a 
small,  directly  driven  rotary  oiler  feeds  oil  to  the  base 
of  each  individual  cylinder.  The  supply  of  oil  is  fur- 
nished by  the  main  oil  pump  located  in  the  lower  crank- 
case.  A  small  sight-feed  regulator  is  furnished  to  control 
the  supply  of  oil  from  this  oiler.  This  instrument  should 
be  placed  higher  than  the  auxiliary  oil  distributor  itself 
to  enable  the  oil  to  drain  by  gravity  feed  to  the  oiler. 
If  there  is  no  available  place  with  the  necessary  height 
in  the  front  seat  of  plane,  connect  it  directly  to  the  intake 
L  fitting  on  the  oiler  in  an  upright  position.  It  should 


214  Aviation  Engines 

be  regulated  with  full  open  throttle  to  maintain  an  oil 
level  in  the  glass,  approximately  half  way. 

An  oil  pressure  gauge  is  provided.  This  should  be  run 
to  the  pilot's  instrument  board.  The  gauge  registers  the 
oil  pressure  upon  the  bearings,  also  determining  its  cir- 
culation. Strict  watch  should  be  maintained  of  this  in- 
strument by  pilot,  and  if  for  any  reason  its  hand  should 
drop  to  0  the  motor  should  be  immediately  stopped  and 
the  trouble  found  before  restarting  engine.  Care  should 
be  taken  that  the  oil  does  not  work  up  into  the  gauge, 
as  it  will  prevent  the  correct  gauge  registering  of  oil 
pressure.  The  oil  pressure  will  vary  according  to  weather 
conditions  and  viscosity  of  oil  used.  In  normal  weather, 
with  the  engine  properly  warmed  up,  the  pressure  will 
register  on  the  oil  gauge  from  5  to  10  pounds  when  the 
engine  is  turning  from  1,275  to  1,300  r.  p.  m.  This  does 
not  apply  to  all  aviation  engines,  however,'  as  the  proper 
pressure  advised  for  the  Curtiss  0X2  motor  is  from  40 
to  55  pounds  at  the  gauge. 

The  oil  sump  plug  is  located  at  the  lowest  point  of 
the  lower  crank-case.  This  is  a  combination  dirt,  water 
and  sediment  trap.  It  is  easily  removed  by  unscrewing. 
Oil  is  furnished  mechanically  to  the  cam-shaft  housing 
under  pressure  through  a  small  tube  leading  from  the 
main  distributing  pipe  at  the  propeller  end  of  engine 
directly  into  the  end  of  cam-shaft  housing.  The  opposite 
end  of  this  housing  is  amply  relieved  to  allow  the  oil 
to  rapidly  flow  down  upon  cam-shaft,  magneto,  pinion- 
shaft,  and  crank-shaft  gears,  after  which  it  returns  to 
lower  crank-case.  An  outside  overflow  pipe  is  also  pro- 
vided to  carry  away  the  surplus  oil. 

DRAINING  OIL  FROM:  CRANK-CASE 

The  oil  strainer  is  placed  at  the  lowest  point  of  the 
lower  crank-case.  This  strainer  should  be  removed  after 
every  five  to  eight  hours  running  of  the  engine  and 
cleaned  thoroughly  with  gasoline.  It  is  also  advisable 
to  squirt  distillate  up  into  the  case  through  the  opening 


Hall-Scott  Oiling  System  215 

where  the  strainer  has  been  removed.  Allow  this  dis- 
tillate to  drain  out  thoroughly  before  replacing  the  plug 
with  strainer  attached.  Be  sure  gasket  is  in  place  on 
plug  before  replacing.  Pour  new  oil  in  through  either 
of  the  two  breather  pipes  on  exhaust  side  of  motor. 
Be  sure  to  replace  strainer  screens  if  removed.  If, 
through  oversight,  the  engine  does  not  receive  sufficient 
lubrication  and  begins  to  heat  or  pound,  it  should  be 
stopped  immediately.  After  allowing  engine  to  cool  pour 
at  least  three  gallons  of  oil  into  oil  sump.  Fill  radiator 
with  water  after  engine  has  cooled.  Should  there  be 
apparent  damage,  the  engine  should  be  thoroughly  in- 
spected immediately  without  further  running.  If  no  ob- 
vious damage  has  been  done,  the  engine  should  be  given 
a  careful  examination  at  the  earliest  opportunity  to  see 
that  the  running  without  oil  has  not  burned  the  bearings 
or  caused  other  trouble. 

Oils  best  adapted  for  Hall-Scott  engines  have  the  fol- 
lowing properties:  A  flash  test  of  not  less  than  400°  F. ; 
viscosity  of  not  less  than  75  to  85  taken  at  20°  F.  with 
Saybolt's  Universal  Viscosimeter. 

Zeroline  heavy  duty  oil,  manufactured  by  the  Standard 
Oil  Company  of  California;  also, 

Gargoyle  mobile  B  oil,  manufactured  by  the  Vacuum 
Oil  Company,  both  fulfill  the  above  specifications.  One 
or  the  other  of  these  oils  can  be  obtained  all  over  the 
world. 

Monogram  extra  heavy  is  also  recommended. 

OIL    SUPPLY    BY    CONSTANT    LEVEL    SPLASH    SYSTEM 

The  splash  system  of  lubrication  that  depends  on  the 
connecting  rod  to  distribute  the  lubricant  is  one  of  the 
most  successful  and  simplest  forms  for  simple  four-  and 
six-cylinder  vertical  automobile  engines,  but  is  not  as 
well  adapted  to  the  oiling  of  airplane  power  plants  for 
reasons  previously  stated.  If  too  much  oil  is  supplied 
the  surplus  will  work  past  the  piston  rings  and  into  the 
combustion  chamber,  where  it  will  burn  and  cause  carbon 


216  Aviation  Engines 

deposits.  Too  much  oil  will  also  cause  an  engine  to  smoke 
and  an  excess  of  lubricating  oil  is  usually  manifested 
by  a  bluish- white  smoke  issuing  from  the  exhaust. 

A  good  method  of  maintaining  a  constant  level  of  oil 
for  the  successful  application  of  the  splash  system  is 
shown  at  Fig.  78.  The  engine  base  casting  includes  a 
separate  chamber  which  serves  as  an  oil  container  and 
which  is  below  the  level  of  oil  in  the  crank-case.  The 
lubricant  is  drawn  from  the  sump  or  oil  container  by 
means  of  a  positive  oil  pump  which  discharges  directly 
into  the  engine  case.  The  level  is  maintained  by  an  over- 
flow pipe  which  allows  all  excess  lubricant  to  flow  back 
into  the  oil  container  at  the  bottom  of  the  cylinder. 
Before  passing  into  the  pump  again  the  oil  is  strained 
or  filtered  by  a  screen  of  wire  gauze  and  all  foreign 
matter  removed.  Owing  to  the  rapid  circulation  of  the 
oil  it  may  be  used  over  and  over  again  for  quite  a  period 
of  time.  The  oil  is  introduced  directly  into  the  crank- 
case  by  a  breather  pipe  and  the  level  is  indicated  by 
a  rod  carried  by  a  float  which  rises  when  the  container  is 
replenished  and  falls  when  the  available  supply  dimin- 
ishes. It  will  be  noted  that  with  such  system  the  only 
apparatus  required  besides  the  oil  tank  which  is  cast 
integral  with  the  bottom  of  the  crank-case  is  a  suitable 
pump  to  maintain  circulation  of  oil.  This  member  is 
always  positively  driven,  either  by  means  of  shaft  and 
universal  coupling  or  direct  gearing.  As  the  system  is 
entirely  automatic  in  action,  it  will  furnish  a  positive 
supply  of  oil  at  all  desired  points,  and  it  cannot  be 
tampered  with  by  the  inexpert  because  no  adjustments 
are  provided  or  needed. 

DKY   CRANK-CASE   SYSTEM   BEST   FOR  AIRPLANE  ENGINES 

In  most  airplane  power  plants  it  is  considered  desirable 
to  supply  the  oil  directly  to  the  parts  needing  it  by  suit- 
able leads  instead  of  depending  solely  upon  the  distrib- 
uting action  of  scoops  on  the  connecting  rod  big  ends. 
A  system  of  this  nature  is  shown  at  Fig.  77.  The  oil 


Best  Oiling  System  for  Airplane 


217 


is  carried  in  the  crank-case,  as  is  common  practice,  but 
the  normal  oil  level  is  below  the  point  where  it  will  be 
reached  by  the  connecting  rod.  It  is  drawn  from  the 
crank-case  by  a  plunger  pump  which  directs  it  to  a  mani- 
fold leading  directly  to  conductors  which  supply  the  main 


Wafer  Outfetr 


WaterSpac&s 


WaferSpaces 


Geared  0// Pts/n/? 


Fig.  78. — Sectional  View  of  Typical  Motor  Showing  Parts  Needing  Lubri- 
cation and  Method  of  Applying  Oil  by  Constant  Level  Splash  System. 
Note  also  Water  Jacket  and  Spaces  for  Water  Circulation. 


218 


Aviation  Engines 


journals.  After  the  oil  has  been  used  on  these  points  it 
drains  back  into  the  bottom  of  the  crank-case.  An  excess 
is  provided  which  is  supplied  to  the  connecting  rod  ends 
by  passages  drilled  into  the  webs  of  the  crank-shaft  and 
part  way  into  the  crank-pins  as  shown  by  the  dotted 
lines.  The  oil  which  is  present  at  the  connecting  rod 


Oil  Strainer. 
Adjusting  Valve. 
Oil  Filler. 


Reservoir. 


11  Pump. 


Fig.  79.— Pressure  Feed  Oil-Supply*  System  of  Airplane  Power  Plants  has 
Many  Good  Features. 

crank-pins  is  thrown  off  by  centrifugal  force  and  lubri- 
cates the  cylinder  walls  and  other  internal  parts.  Kegu- 
lating  screws  are  provided  so  that  the  amount  of  oil 
supplied  the  different  points  may  be  regulated  at  will. 
A  relief  check  valve  is  installed  to  take  care  of  excess 
lubricant  and  to  allow  any  oil  that  does  not  pass  back 
into  the  pipe  line  to  overflow  or  bi-pass  into  the  main 
container. 

A  simple  system  of  this  nature  is  shown  graphically 
in  a  phantom  view  of  the  crank-case  at  Fig.  79,  in  which 


Why  Cooling  Systems  Are  Needed  219 

the  oil  passages  are  made  specially  prominent.  The  oil 
is  taken  from  a  reservoir  at  the  bottom  of  the  engine 
base  by  the  usual  form  of  gear  oil  pump  and  is  supplied 
to  a  main  feed  manifold  which  extends  the  length  of  the 
crank-case.  Individual  conductors  lead  to  the  five  main 
bearings,  which  in  turn  supply  the  crank-pins  by  pas- 
sages drilled  through  the  crank-shaft  web.  In  this  power 
plant  the  connecting  rods  are  hollow  section  bronze 
castings  and  the  passage  through  the  center  of  the  con- 
necting rod  serves  to  convey  the  lubricant  from  the 
crank-pins  to  the  wrist-pins.  The  cylinder  walls  are  oiled 
by  the  spray  of  lubricant  thrown  off  the  revolving  crank- 
shaft by  centrifugal  force.  Oil  projection  by  the  dippers 
on  the  connecting  rod  ends  from  constant  level  troughs 
is  unequal  upon  the  cylinder  walls  of  the  two-cylinder 
blocks  of  an  eight-  or  twelve-cylinder  V  engine.  This 
gives  rise,  on  one  side  of  the  engine,  to  under-lubrication, 
and,  on  the  other  side,  to  over-lubrication,  as  shown  at 
Fig.  80,  A.  This  applies  to  all  modifications  of  splash 
lubricating  systems. 

When  a  force-feed  lubricating  system  is  used,  the  oil, 
escaping  past  the  cheeks  of  both  ends  of  the  crank-pin 
bearings,  is  thrown  off  at  a  tangent  to  the  crank-pin 
circle  in  all  directions,  supplying  the  cylinders  on  both 
sides  with  an  equal  quantity  of  oil,  as  at  Fig.  80,  B. 

WHY    COOLING   SYSTEMS   ARE    NECESSARY 

The  reader  should  understand  from  preceding  chap- 
ters that  the  power  of  an  internal-combustion  motor  is 
obtained  by  the  rapid  combustion  and  consequent  ex- 
pansion of  some  inflammable  gas.  The  operation  in 
brief  is  that  when  air  or  any  other  gas  or  vapor  is 
heated,  it  will  expand  and  that  if  this  gas  is  confined 
in  a  space  which  will  not  permit  expansion,  pressure  will 
be  exerted  against  all  sides  of  the  containing  chamber. 
The  more  a  gas  is  heated,-  the  more-  pressure  it  will 
exert  upon  the  walls  of  the  combustion  chamber  it 


220 


Aviation  Engines 


B 


Fig.    80. — Why   Pressure    Feed    System    is    Best    for   Eight-Cylinder    Vee 

Airplane  Engines. 


Why  Cooling  Systems  are  Needed  221 

confines.  Pressure  in  a  gas  may  be  created  by  increasing 
its  temperature  and  inversely  heat  may  be  created  by 
pressure.  When  a  gas  is  compressed  its  total  volume  is 
reduced  and  the  temperature  is  augmented. 

The  efficiency  of  any  form  of  heat  engine  is  deter- 
mined by  the  power  obtained  from  a  certain  fuel  con- 
sumption. A  definite  amount  of  energy  will  be  liberated 
in  the  form  of  heat  when  a  pound  of  any  fuel  is  burned. 
The  efficiency  of  any  heat  engine  is  proportional  to  the 
power  developed  from  a  definite  quantity  of  fuel  with  the 
least  loss  of  thermal  units.  If  the  greater  proportion 
of  the  heat  units  derived  by  burning  the  explosive  mix- 
ture could  be  utilized  in  doing  useful  work,  the  efficiency 
of  the  gasoline  engine  would  be  greater  than  that  of 
any  other  form  of  energizing  power.  There  is  a  great 
loss  of  heat  from  various  causes,  among  which  can  be 
cited  the  reduction  of  pressure  through  cooling  the  motor 
and  the  loss  of  heat  through  the  exhaust  valves  when 
the  burned  gases  are  expelled  from  the  cylinder. 

The  loss  through  the  water  jacket  of  the  average  auto- 
mobile power  plant  is  over  50  per  cent,  of  the  total  fuel 
efficiency.  This  means  that  more  than  half  of  the  heat 
units  available  for  power  are  absorbed  and  dissipated 
by  the  cooling  water.  Another  16  per  cent,  is  lost  through 
the  exhaust  valve,  and  but  33%  per  cent,  of  the  heat 
units  do  useful  work.  The  great  loss  of  heat  through 
the  cooling  systems  cannot  be  avoided,  as  some  method 
must  be  provided  to  keep  the  temperature  of  the  engine 
within  proper  bounds.  It  is  apparent  that  the  rapid 
combustion  and  continued  series  of  explosions  would 
soon  heat  the  metal  portions  of  the  engine  to  a  red  heat 
if  some  means  were  not  taken  to  conduct  much  of  this 
heat  away.  The  high  temperature  of  the  parts  would 
burn  the  lubricating  oil,  even  that  of  the  best  quality, 
and  the  piston  and  rings  would  expand  to  such  a  degree, 
especially  when  deprived  of  oil,  that  they  would  seize  in 
the  cylinder.  This  would  score  the  walls,  and  the  friction 
which  ensued  would  tend  to  bind  the  parts  so  tightly 


222 


Aviation  Engines 


that  the  piston  would  stick,  bearings  would  be  burned 
out,  the  valves  would  warp,  and  the  engine  would  soon 
become  inoperative. 

The  best  temperature  to  secure  efficient  operation  is 
one  on  which  considerable  difference  of  opinion  exists 
among  engineers.  The  fact  that  the  efficiency  of  an 
engine  is  dependent  upon  the  ratio  of  heat  converted 


Cylinder  Walls 
1 80 "to  550°  Fahr. 


,Heat  of  Explosion  2000 c 'to  3000° Fahr. 


.  Piston  Heads 
'  300°iolOOO°Fahr. 


.Pision  Walls 
;200°to400°Fahr 


Crank  Bearing  Oil        /' 
140 "to  250°  Fahr  ,*' 


Sump  Oil  90°  to  200  °Fahr/ 


Fig.  81. — Operating  Temperatures  of  Automobile  Engine  Parts  Useful  as  a 
Guide  to  Understand  Airplane  Power  Plant  Heat. 

into  useful  work  compared  to  that  generated  by  the 
explosion  of  the  gas  is  an  accepted  fact.  It  is  very 
important  that  the  engine  should  not  get  too  hot,  and 
on  the  other  hand  it  is  equally  vital  that  the  cylinders 
be  not  robbed  of  too  much  heat.  The  object  of  cylinder 
cooling  is  to  keep  the  temperature  of  the  cylinder  below 
the  danger  point,  but  at  the  same  time  to  have  it  as 
high  as  possible  to  secure  maximum  power  from  the 
gas  burned.  The  usual  operating  temperatures  of  an 


Cooling  Systems  Generally  Applied  223 

automobile  engine  are  shown  at  Fig.  81,  and  this  can 
be  taken  as  an  approximation  of  the  temperatures  apt  to 
exist  in  an  airplane  engine  of  conventional  design  as  well 
when  at  ground  level  or  not  very  high  in  the  air.  The 
newer  very  high  compression  airplane  engines  in  which 
compressions  of  eight  or  nine  atmospheres  are  used,  or 
about  125  pounds  per  square  inch,  will  run  considerably 
hotter  than  the  temperatures  indicated. 


COOLING    SYSTEMS    GENERALLY    APPLIED 

There  are  two  general  systems  of  engine  cooling  in 
common  use,  that  in  which  water  is  heated  by  the  ab- 
sorption of  heat  from  the  engine  and  then  cooled  by  air, 
and  the  other  method  in  which  the  air  is  directed  onto 
the  cylinder  and  absorbs  the  heat  directly  instead  of 
through  the  medium  of  water.  When  the  liquid  is  em- 
ployed in  cooling  it  is  circulated  through  jackets  which 
surround  the  cylinder  casting  and  the  water  may  be 
kept  in  motion  by  two  methods.  The  one  generally 
favored  is  to  use  a  positive  circulating  pump  of  some 
form  which  is  driven  by  the  engine  to  keep  the  water 
in  motion.  The  other  system  is  to  utilize  a  natural 
principle  that  heated  water  is  lighter  than  cold  liquid 
and  that  it  will  tend  to  rise  to  the  top  of  the  cylinder 
when  it  becomes  heated  to  the  proper  temperature  and 
cooled  water  takes  its  place  at  the  bottom  of  the  water 
jacket. 

Air-cooling  methods  may  be  by  radiation  or  convec- 
tion. In  the  former  case  the  effective  outer  surface  of 
the  cylinder  is  increased  by  the  addition  of  flanges 
machined  or  cast  thereon,  and  the  air  is  depended  on 
to  rise  from  the  cylinder  as  heated  and  be  replaced  by 
cooler  air.  This,  of  course,  is  found  only  on  stationary 
engines.  When  a  positive  air  draught  is  directed  against 
the  cylinder  by  means  of  the  propeller  slip  stream  in 
an  airplane,  cooling  is  by  convection  and  radiation  both. 
Sometimes  the  air  draught  may  be  directed  against  the 


224 


Aviation  Engines 


cylinder  walls  by  some  form  of  jacket  which  confines  it 
to  the  heated  portions  of  the  cylinder. 

COOLING    BY    POSITIVE    WATER    CIRCULATION 

A  typical  water-cooling  system  in  which  a  pump  is 
depended  upon  to  promote  circulation  of  the  cooling 
liquid  is  shown  at  Figs.  82  and  83.  The  radiator  is  car- 
ried at  the  front  end  of  the  fuselage  in  most  cases,  and 
serves  as  a  combined  water  tank  and  cooler,  but  in  some 
cases  it  is  carried  at  the  side  of  the  engine,  as  in  Fig. 


.Outlet  Pipes  for  Hot  Wafer 


Filler 


Centrifugal" 
Pump 


Centrifugal 
Pump 


Fig.  82. — Water  Cooling  of  Salmson  Seven-Cylinder  Radial  Airplane  Engine. 

84,  or  attached  to  the  central  portion  of  the  aerofoil  or 
wing  structure.  It  is  composed  of  an  upper  and  lower 
portion  joined  together  by  a  series  of  pipes  which  may 
be  round  and  provided  with  a  series  of  fins  to  radiate 
the  heat,  or  which  may  be  flat  in  order  to  have  the  water 
pass  through  in  thin  sheets  and  cool  it  more  easily. 
Cellular  or  honeycomb  coolers  are  composed  of  a  large 
number  of  bent  tubes  which  will  expose  a  large  area  of 
surface  to  the  cooling  influence  of  the  air  draught  forced 
through  the  radiator  either  by  the  forward  movement 
of  the  vehicle  or  by  some  type  of  fan.  The  cellular  and 


Cooling  by  Positive  Circulation 


225 


flat  tube  types  have  almost  entirely  displaced  the  flange 
tube  radiators  which  were  formerly  popular  because  they 
cool  the  water  more  effectively,  and  may  be  made  lighter 
than  the  tubular  radiator  could  be  for  engines  of  the 
same  capacity. 

The  water  is   drawn  from  the  lower  header   of   the 
radiator  by  the  pump  and  is  forced  through  -a  manifold 


fPU-Tracf-o/*  Scre\ 


'Radiator,  -Hot-Water  P/pe.      / 


Filler  Cafi     I        Hose  for 

Flexible  Connection 


Pipe  from 


foPvmp 


Pipe  from 
Bottom  of 
Radiator  to 

Water  Pump 


r  Lurrenr 
ongerons 
Engirt  e.  Bed 


Fig.    83. — How    Water    Cooling    System    of    Thomas    Airplane    Engine    is 
Installed  in  Fuselage. 

to  the  lower  portion  of  the  water  jackets  of  the  cylinder. 
It  becomes  heated  as  it  passes  around  the  cylinder  walls 
and  combustion  chambers  and  the  hot  water  passes  out 
of  the  top  of  the  water  jacket  to  the  upper  portion  of 
the  radiator.  Here  it  is  divided  in  thin  streams  and 
directed  against  comparatively  cool  metal  which  abstracts 
the  heat  from  the  water.  As  it  becomes  cooler  it  falls 
to  the  bottom  of  the  radiator  because  its  weight  increases 
as  the  temperature  becomes  lower.  By  the  time  it  reaches 


226 


Aviation  Engines 


the  lower  tank  of  the  radiator  it  has  been  cooled  suffi- 
ciently so.  that  it  may  be  again  passed  around  the  cylin- 
ders of  the  motor.  The  popular  form  of  circulating 
pump  is  known  as  the  "centrifugal  type"  because  a  rotary 
impeller  of  paddle-wheel  form  throws  water  which  it 
receives  at  a  central  point  toward  the  outside  and  thus 
causes  it  to  maintain  a  definite  rate  of  circulation.  The 
pump  is  always  a  separate  appliance  attached  to  the 


Fig.  84. — Finned  Tube  Radiators  at  the  Side  of  Hall-Scott  Airplane  Power 
Plant  Installed  in  Standard  Fuselage. 

engine  and  driven  by  positive  gearing  or  direct-shaft 
connection.  The  centrifugal  pump  is  not  as  positive  as 
the  gear  form,  and  some  manufacturers  prefer  the  latter 
because  of  the  positive  pumping  features.  They  are 
very  simple  in  form,  consisting  of  a  suitable  cast  body 
in  which  a  pair  of  spur  pinions  having  large  teeth  are 
carried.  One  of  these  gears  is  driven  by  suitable  means, 
and  as  it  turns  the  other  member  they  maintain  a  flow 
of  water  around  the  pump  body.  •  The  pump  should  al- 
ways be  installed  in  series  with  the  water  pipe  which 


Water  Circulation  by  Natural  System          227 

conveys  the  cool  liquid  from  the  lower  compartment  of  the 
radiator  to  the  coolest  portion  of  the  water  jacket. 

WATER    CIRCULATION    BY    NATURAL    SYSTEM 

Some  automobile  engineers  contend  that  the  rapid 
water  circulation  obtained  by  using  a  pump  may  cool 
the  cylinders  too  much,  and  that  the  temperature  of  the 
engine  may  be  reduced  so  much  that  the  efficiency  will 
be  lessened.  For  this  reason  there  is  a  growing  tendency 
to  use  the  natural  method  of  water  circulation  as  the 
cooling  liquid  is  supplied  to  the  cylinder  jackets  just 
below  the  boiling  point,  and  the  water  issues  from  the 
jacket  at  the  top  of  the  cylinder  after  it  has  absorbed 
sufficient  heat  to  raise  it  just  about  to  the  boiling  point. 

As  the  water  becomes  heated  by  contact  with  the  hot 
cylinder  and  combustion-chamber  walls  it  rises  to  the  top 
of  the  water  ;jacket,  flows  to  the  cooler,  where  enough 
of  the  heat  is  absorbed  to  cause  it  to  become  sensibly 
greater  in  weight.  As  the  water  becomes  cooler,  it  falls 
to  the  bottom  of  the  radiator  and  it  is  again  supplied 
to  the  water  jacket.  The  circulation  is  entirely  automatic 
and  continues  as  long  as  there  is  a  difference  in  tem- 
perature between  the  liquid  in  the  water  spaces  of  the 
engine  and  that  in  the  cooler.  The  circulation  becomes 
brisker  as  the  engine  becomes  hotter  and  thus  the  tem- 
perature of  the  cylinders  is  kept  more  nearly  to  a  fixed 
point.  "With  the  thermosyphon  system  the  cooling  liquid 
is  nearly  always  at  its  boiling  point,  whereas  if  the  cir- 
culation is  maintained  by  a  pump  the  engine  will  become 
cooler  at  high  speed  and  will  heat  up  more  at  low  speed. 

With  the  thermosyphon,  or  natural  system  of  cooling, 
more  water  must  be  carried  than  with  the  pump-main- 
tained circulation  methods.  The  water  spaces  around 
the  cylinders  should  be  larger,  the  inlet  and  discharge 
water  manifolds  should  have  greater  capacity,  and  be 
free  from  sharp  corners  which  might  impede  the  flow. 
The  radiator  must  also  carry  more  water  than  the  form 
used  in  connection  with  the  pump  because  of  the  brisker 


228  Aviation  Engines 

pump  circulation  which  maintains  the  engine  temperature 
at  a  lower  point.  Consideration  of  the  above  will  show 
why  the  pump  system  is  almost  universally  used  in 
connection  with  airplane  power  plant  cooling. 

DIRECT    AIK-COOLING    METHODS 

The  earliest  known  method  of  cooling  the  cylinder 
of  gas-engines  was  by  means  of  a  current  of  air  passed 
through  a  jacket  which  confined  it  close  to  the  cylinder 
walls  and  was  used  by  Daimler  on  his  first  gas-engine. 
The  gasoline  engine  of  that  time  was  not  as  efficient  as 
the  later  form,  and  other  conditions  which  materialized 
made  it  desirable  to  cool  the  engine  by  water.  Even  as 
gasoline  engines  became  more  and  more  perfected  there 
has  always  existed  a  prejudice  against  air  cooling,  though 
many  forms  of  engines  have  been  used,  both  in  automo- 
bile and  aircraft  applications  where  the  air-cooling  method 
has  proven  to  be  very  practical. 

The  simplest  system  of  air  cooling  is  that  in  which 
the  cylinders  are  provided  with  a  series  of  flanges  which 
increase  the  effective  radiating  surface  of  the  cylinder 
and  directing  an  air  current  from  a  fan  against  the 
flanges  to  absorb  the  heat.  This  increase  in  the  avail- 
able radiating  surface  of  an  air-cooled  cylinder  is  neces- 
sary because  air  does  not  absorb  heat  as  readily  as  water 
and  therefore  more  surface  must  be  provided  that  the 
excess  heat  be  absorbed  sufficiently  fast  to  prevent  dis- 
tortion of  the  cylinders.  Air-cooling  systems  are  based 
on  a  law  formulated  by  Newton,  which  is:  "The  rate  for 
cooling  for  a  body  in  a  uniform  current  of  air  is  directly 
proportional  to  the  speed  of  the  air  current  and  the 
amount  of  radiating  surface  exposed  to  the  cooling 
effect." 

AIR-COOLED     ENGINE     DESIGN"     CONSIDERATIONS 

There  are  certain  considerations  which  must  be  taken 
into  account  in  designing  an  air-cooled  engine,  which  are 
often  overlooked  in  those  forms  cboled  by  water.  Large 


Air-Cooled  Engines 


229 


valves  must  be  provided  to  insure  rapid  expulsion  of 
the  flaming  exhaust  gas  and  also  to  admit  promptly  the 
fresh  cool  mixture  from  the  carburetor.  The  valves  of 
air-cooled  engines  are  usually  placed  in  the  cylinder- 


Tracfor  Screw 

Air  Cooled  Flanged  Cylinde. 


Fig.  85.— Anzani  Testing  His  Five-Cylinder  Air  Cooled  Aviation  Motor 
Installed  in  Bleriot  Monoplane.  Note  Exposure  of  Flanged  Cylinders 
to  Propeller  Slip  Stream. 

head,  in  order  to  eliminate  any  pockets  or  sharp  passages 
which  would  impede  the  flow  of  gas  or  retain  some  of 
the  products  of  combustion  and  their  heat.  When  high 
power  is  desired  multiple-cylinder  engines  should  be  used, 
as  there  is  a  certain  limit  to  the  size  of  a  successful 


230  Aviation  Engines 

air-cooled  cylinder.  Much  better  results  are  secured  from 
those  having  small  cubical  contents  because  the  heat  from 
small  quantities  of  gas  will  be  more  quickly  carried  off 
than  from  greater  amounts.  All  successful  engines  of 
the  aviation  type  which  have  been  air-cooled  have  been 
of  the  multiple-cylinder  type. 

An  air-cooled  engine  must  be  placed  in  .the  fuselage, 
as  at  Fig.  85,  in  such  a  'way  that  there  will  be  a  positive 
circulation  of  air  around  it  all  the  time  that  it  is  in 
operation.  The  air  current  may  be  produced  by  the 
tractor  screw  at  the  front  end  of  the  motor,  or  by  a 
suction  or  blower  fan  attached  to  the  crank-shaft  as  in  the 
Eenault  engine  or  by  rotating  the  cylinders  as  in  the 
Le  Khone  and  Gnome  motors.  Greater  care  is  required 
in  lubrication  of  the  air-cooled  cylinders  and  only  the  best 
quality  of  oil  should  be  used  to  insure  satisfactory  oiling. 

The  combustion  chambers  must  be  proportioned  so 
that  distribution  of  metal  is  as  uniform  as  possible  in 
order  to  prevent  uneven  expansion  during  increase  in 
temperature  and  uneven  contraction  when  the  cylinder 
is  cooled.  It  is  essential  that  the  inside  walls  of  the 
combustion  chamber  be  as  smooth  as  possible  because 
any  sharp  angle  or  projection  may  absorb  sufficient  heat 
to  remain  incandescent  and  cause  trouble  by  igniting  the 
mixture  before  the  proper  time.  The  best  grades  of  cast 
iron  or  steel  should  be  used  in  the  cylinder  and  piston 
and  the  machine  work  must  be  done  very  accurately 
so  the  piston  will  operate  with  minimum  friction  in  the 
cylinder.  The  cylinder  bore  should  not  exceed  4%  or  5 
inches  and  the  compression  pressure  should  never  exceed 
75  pounds  absolute,  or  about  five  atmospheres,,  or  serious 
overheating  will  result. 

As  an  example  of  the  care  taken  in  disposing  of  the 
exhaust  gases  in  order  to  obtain  practical  air-cooling, 
some  cylinders  are  provided  with  a  series  of  auxiliary 
exhaust  ports  uncovered  by  the  piston  when  it  reaches 
the  end  of  its  power  stroke.  The  auxiliary  exhaust  ports 
open  just  as  soon  as  the  full  force  of  the  explosion  has 


Air-Cooling  Methods  231 

been  spent  and  a  portion  of  the  flaming  gases  is  dis- 
charged through  the  ports  in  the  bottom  of  the  cylinder. 
Less  of  the  exhaust  gases  remains  to  be  discharged 
through  the  regular  exhaust  member  in  the  cylinder-head 
and  this  will  not  heat  the  walls  of  the  cylinder  nearly 
as  much  as  the  larger  quantity  of  hot  gas  would.  That 
the  auxiliary  exhaust  port  is  of  considerable  value  is 
conceded  by  many  designers  of  fixed  and  fan-shaped  air- 
cooled  motors  for  airplanes. 

Among  the  advantages  stated  for  direct  air  cooling, 
the  greatest  is  the  elimination  of  cooling  water  and  its 
cooling  auxiliaries,  which  is  a  factor  of  some  moment, 
as  it  permits  considerable  reduction  in  horse-power-weight 
ratio  of  the  engine,  something  very  much  to  be  desired. 
In  the  temperate  zone,  where  the  majority  of  airplanes 
are  used,  the  weather  conditions  change  in  a  very  few 
months  from  the  warm  summer  to  the  extreme  cold 
winter,  and  when  water-cooled  systems  are  employed  it  is 
necessary  to  add  some  chemical  substance  to  the  water 
to  prevent  it  from  freezing.  The  substances  commonly 
employed  are  glycerine,  wood  alcohol,  or  a  saturated 
solution  of  calcium  chloride.  Alcohol  has  the  disadvan- 
tage in  that  it  vaporizes  readily  and  must  be  often  re- 
newed. Glycerine  affects  the  rubber  hose,  while  the 
calcium  chloride  solution  crystallizes  and  deposits  salt 
in  the  radiator  and  water  pipes. 

One  of  the  disadvantages  of  an  air-cooling  method, 
as  stated  by  those  who  do  not  favor  this  system,  is  that 
engines  cooled  by  air  cannot  be  operated  for  extended 
periods  under  constant  load  or  at  very  high  speed  with- 
out heating  up  to  such  a  point  that  premature  ignition 
of  the  charge  may  result.  The  water-cooling  systems, 
at  the  other  hand,  maintain  the  temperature  of  the  engine 
more  nearly  constant  than  is  possible  with  an  air-cooled 
motor,  and  an  engine  cooled  by  water  can  be  operated 
under  conditions  of  inferior  lubrication  or  poor  mixture 
adjustment  that  would  seriously  interfere  with  proper 
and  efficient  cooling  by  air. 


232  Aviation  Engines 

Air-cooled  motors,  as  a  rule,  use  less  fuel  than  water- 
cooled  engines,  because  the  higher  temperature  of  the 
cylinder  does  not  permit  of  a  full  charge  of  gas  being 
inspired  on  the  intake  stroke.  As  special  care  is  needed 
in  operating  an  air-cooled  engine  to  obtain  satisfactory 
results  and  because  of  the  greater  difficulty  which  obtains 
in  providing  proper  lubrication  and  fuel  mixturers  which 
will  not  produce  undue  heating,  the  air-cooled  system 
has  but  few  adherents  at  the  present  time,  and  practically 
all  airplanes,  with  but  very  few  exceptions,  are  provided 
with  water-cooled  .power  plants.  Those  fitted  with  air- 
cooled  engines  are  usually  short-flight  types  where  maxi- 
mum lightness  is  desired  in  order  to  obtain  high  speed 
and  quick  climb.  The  water-cooled  engines  are  best 
suited  for  airplanes  intended  for  long  flights.  The  Gnome, 
Le  Ehone  and  Clerget  engines  are  thoroughly  practical 
and  have  been  widely  used  in  France  and  England. 
These  are  rotary  radial  cylinder  types.  The  Anzani  is 
a  fixed  cylinder  engine  used  on  training  machines,  while 
the  Renault  is  a  V-type  engine  made  in  eight-  and  twelve- 
cylinder  V  forms  that  has  been  used  on  reconnaissance 
and  bombing  airplanes  with  success.  These  types  will 
be  fully  considered  in  proper  sequence. 


CHAPTER    VIII 

Methods  of  Cylinder  Construction — Block  Castings — Influence  on 
Crank-Shaft  Design — Combustion  Chamber  Design— Bore  and 
Stroke  Ratio — Meaning  of  Piston  Speed — Advantage  of  Off-Set 
Cylinders— Valve  Location  of  Vital  Import — Valve  Installation 
Practice — Valve  Design  and  Construction — Valve  Operation — 
Methods  of  Driving  Cam-Shaft — Valve  Springs — Valve  Timing — 
Blowing  Back — Lead  Given  Exhaust  Valve — Exhaust  Closing, 
Inlet  Opening — Closing  the  Inlet  Valve — Time  of  Ignition — How 
an  Engine  Is  Timed — Gnome  "Monosoupape"  Valve  Timing — 
Springless  Valves — Four  Valves  per  Cylinder. 

THE  improvements  noted  in  the  modern  internal  com- 
bustion motors  have  been  due  to  many  conditions.  The 
continual  experimenting  by  leading  mechanical  minds 
could  have  but  one  ultimate  result.  The  parts  of  the 
engines  have  been  lightened  and  strengthened,  and  greater 
power  has  been  obtained  without  increasing  piston  dis- 
placement. A  careful  study  has  been  made  of  the  many 
conditions  which  make  for  efficient  motor  action,  and 
that  the  main  principles  are  well  recognized  by  all  en- 
gineers is  well  shown  by  the  standardization  of  design 
noted  in  modern  power  plants.  There  are  many  different 
methods  of  applying  the  same  principle,  and  it  will  be 
the  purpose  of  this  chapter  to  define  the  ways  in  which 
the  construction  may  be  changed  and  still  achieve  the 
same  results.  The  various  components  may  exist  in  many 
different  forms,  and  all  have  their  advantages  and  dis- 
advantages. That  all  methods  are  practical  is  best  shown 
by  the  large  number  of  successful  engines  which  use 
radically  different  designs. 

METHODS    OF    CYLINDER    CONSTRUCTION 

One  of  the  most  important  parts  of  the  gasoline 
engine  and  one  that  has  material  bearing  upon  its  effi- 
ciency is  the  cylinder  unit.  The  cylinders  may  be  cast 

233 


234  Aviation  Engines 

individually,  or  in  pairs,  and  it  is  possible  to  make  all 
cylinders  a  unit  or  block  casting.  Some  typical  methods 
of  cylinder  construction  are  shown  in  accompanying  illus- 
trations. The  appearance  of  individual  cylinder  castings 
may  be  ascertained  by  examination  of  the  Hall-Scott 
airplane  engine.  Air-cooled  engine  cylinders  are  always 
of  the  individual  pattern. 

Considered  from  a  purely  theoretical  point  of  view, 
the  individual  cylinder .  casting  has  much  in  its  favor. 
It  is  advanced  that  more  uniform  cooling  is  possible 
than  where  the  cylinders  are  cast  either  in  pairs  or  three 
or  four  in  one  casting.  More  uniform  cooling  insures 
that  the  expansion  or  change  of  form  due  to  heating  will 
be  more  equal.  This  is  an  important  condition  because 
the  cylinder  bore  must  remain  true  under  all  conditions 
of  operation.  If  the  heating  effect  is  not  uniform,  which 
condition  is  liable  to  obtain  if  metal  is  not  evenly  dis- 
tributed, the  cylinder  may  become  distorted  by  heat  and 
the  bore  be  out  of  truth.  When  separate  cylinders  are 
used  it  is  possible  to  make  a  uniform  water  space  and 
have  the  cooling  liquid  evenly  distributed  around  the 
cylinder.  In  multiple  cylinder  castings  this  is  not  always 
the  rule,  as  in  many  instances,  especially  in  four-cylinder 
block  motors  where  compactness  is  the  main  feature,  there 
is  but  little  space  between  the  cylinders  for  the  passage 
of  water.  Under  such  circumstances  the  cooling  effect 
is  not  even,  and  the  stresses  which  obtain  because  of 
unequal  expansion  may  distort  the  cylinder  to  some 
extent.  When  steel  cylinders  are  made  from  forgings, 
the  water  jackets  are  usually  of  copper  or  sheet  steel 
attached  to  the  forging  by  autogenous  welding;  in  the 
case  of  the  latter  and,  in  some  cases,  the  former  may  be 
electro-deposited  on  the  cylinders. 

BLOCK    CASTINGS 

The  advantage  of  casting  the  cylinders  in  blocks  is 
that  a  motor  may  be  much  shorter  than  it  would  be  if 
individual  castings  were  used.  It  is  admitted  that  when 


Block  Casting  of  Cylinders 


235 


the  cylinders  are  cast  together  a  more  compact,  rigid, 
and  stronger  power  plant  is  obtained  than  when  cast 
separately.  There  is  a  disadvantage,  however,  in  that 
if  one  cylinder  becomes  damaged  it  will  be  necessary  to 


@ 


© 


Viewed  -from  Top 


'ocroo/  ooo'O 


Fig.  86. — Views  of  Four-Cylinder  Duesenberg  Airplane  Engine 
Cylinder  Block. 

replace  the  entire  unit,  which  means  scrapping  three 
good  cylinders  because  one  of  the  four  has  failed.  When 
the  cylinders  are  cast  separately  one  need  only  replace 
the  one  that  has  become  damaged.  The  casting  of  four 
cylinders  in  one  unit  is  made  possible  by  improved 


236  Aviation  Engines 

foundry  methods,  and  when  proper  provision  is  made  for 
holding  the  cores  when  the  metal  is  poured  and  the 
cylinder  casts  are  good,  the  construction  is  one  of  dis- 
tinct merit.  It  is  sometimes  the  case  that  the  proportion 
of  sound  castings  is  less  when  cylinders  are  cast  in 
"block,  but  if  the  proper  precautions  are  observed  in 
molding  and  the  proper  mixtures  of  cast  iron  used,  the 
ratio  of  defective  castings  is  no  more  than  when  cylinders 
are  molded  individually.  As  an  example  of  the  courage 
of  engineers  in  departing  from  old-established  rules,  the 
cylinder  casting  shown  at  Fig.  86  may  be  considered 
typical.  This  is  used  on  the  Duesenberg  four-cylinder 
sixteen- valve  4%"  x  7"  engine  which  has  a  piston  dis- 
placement of  496  cu.  in.  At  a  speed  of  2,000  r.p.m., 
corresponding  to  a  piston  speed  of  2,325  ft.  per  min.,  the 
engine  is  guaranteed  to  develop  125  horse-power.  The 
weight  of  the  model  engine  without  gear  reduction  is 
436  Ibs.,  but  a  number  of  refinements  have  been  made  in 
the  design  whereby  it  is  expected  to  get  the  weight  down 
to  390  Ibs.  The  four  cylinders  are  cast  from  semi- steel 
in  a  single  block,  with  integral  heads.  The  cylinder 
construction  is  the  same  as  that  which  has  always 
been  used  by  Mr.  Duesenberg,  inlet  and 'exhaust  valves 
being  arranged  horizontally  opposite  each  other  in  the 
head.  •  There  are  large  openings  in  the  water  jacket 
at  both  sides  and  at  the  ends,  which  are  closed  by  means 
of  aluminum  covers,  water-tightness  being  secured  by 
•the  use  of  gaskets.  This  results  in  a  saving  in  weight 
because  the  aluminum  covers  can  be  made  considerably 
lighter  than  it  would  be  possible  to  cast  the  jacket  walls, 
and,  besides,  it  permits  of  obtaining  a  more  nearly  uni- 
form thickness  of  cylinder  wall,  as  the  cores  can  be 
much  better  supported.  The  cooling  water  passes  com- 
pletely around  each  cylinder,  and  there  is  a  very  con- 
siderable space  between  the  two  central  cylinders,  this 
being  made  necessary  in  order  to  get  the  large  bearing 
area  desirable  for  the  central  bearing. 

It  is  common  practice  to  cast  the  water  jackets  inte- 


Advantage  of  Block  Castings  237 

gral  with  the  cylinders,  if  cast  iron  or  aluminum  is  used, 
and  this  is  also  the  most  economical  method  of  applying 
it  because  it  gives  good  results  in  practice.  An  important 
detail  is  that  the  water  spaces  must  be  proportioned  so 
that  they  are  equal  around  the  cylinders  whether  these 
members  are  cast  individually,  in  pairs,  threes  or  fours. 
When  cylinders  are  cast  in  block  form  it  is  good  practice 
to  leave  a  large  opening  in  the  jacket  wall  which  will 
assist  in  supporting  the  core  and  make  for  uniform  water 
space.  It  will  be  noticed  that  the  casting  shown  at  Fig. 
86  has  a  large  opening  in  the  side  of  the  cylinder  block. 
These  openings  are  closed  after  the  interior  of  the  casting 
is  thoroughly  cleaned  of  all  sand,  core  wire,  etc.,  by  brass, 
cast  iron  or  aluminum  plates.  These  also  have  particular 
value  in  that  they  may  be  removed  after  the  motor  has 
been  in  use,  thus  permitting  one  to  clean  out  the  interior 
of  the  water  jacket  and  dispose  of  the  rust,  sediment,, 
and  incrustation  which  are  always  present  after  the 
engine  has  been  in  active  service  for  a  time. 

Among  the  advantages  claimed  for  the  practice  of 
casting  cylinders  in  blocks  may  be  mentioned  compact- 
ness, lightness,  rigidity,  simplicity  of  water  piping,  as  well 
as  permitting  the  use  of  simple  forms  of  inlet  and  exhaust 
manifolds.  The  light  weight  is  not  only  due-  to  the  reduc- 
tion of  the  cylinder  mass  but  because  the  block  construc- 
tion permits  one  to  lighten  the  entire  motor.  The  fact 
that  all  cylinders  are  cast  together  decreases  vibration, 
and  as  the  construction  is  very  rigid,  disalignment  of 
working  parts  is  practically  eliminated.  When  inlet  and 
exhaust  manifolds  are  cored  in  the  block  casting,  as  is 
sometimes  the  case,  but  one  joint  is  needed  on  each  of 
these  instead  of  the  multiplicity  of  joints  which  obtain 
when  the  cylinders  are  individual  castings.  The  water 
piping  is  also  simplified.  In  the  case  of  a  four-cylinder 
block  motor  but  two  pipes  are  used;  one  for  the  water 
to  enter  the  cylinder  jacket,  the  other  for  the  cooling 
liquid  to  discharge  through. 


238 


Aviation  Engines 


INFLUENCE    ON    CRANK-SHAFT   DESIGN 

The  method  of  casting  the  cylinders  has  a  material 
influence  on  the  design  of  the  crank-shaft  as  will  be  shown 
in  proper  sequence.  When  four  cylinders  are  combined 
in  one  block  it  is  possible  to  use  a  two-bearing  crank-shaft. 
Where  cylinders  are  cast  in  pairs  a  three-bearing  crank- 
shaft is  commonly  supplied,  and  when  cylinders  are  cast 


.Copper  Asbestos  Gasket 


"'Cylinder  Li/ier 

<Aluminum  Cylinder 
Pair  Casting 


.Cylinder 
•'        Head 


Fig.   87. — Twin-Cylinder  Block  of  Sturtevant  Airplane  Engine  is  Cast  of 
Aluminum,  and  Has  Removable  Cylinder  Head. 

as  individual  units  it  is  thought  necessary  to  supply  a 
five-bearing  crank-shaft,  though  sometimes  shafts  having 
but  three  journals  are  used  successfully.  Obviously  the 
shafts  must  be  stronger  and  stiffer  to  withstand  the 
stresses  imposed  if  two  supporting  bearings  are  used 
than  if  a  larger  number  are  employed.  In  this  connec- 
tion it  may  be  stated  that  there  is  less  difficulty  in  secur- 
ing alignment  with  a  lesser  number  of  bearings  and  there 
is  also  less  friction.  On  the  other  hand,  the  greater  the 
number  of  points  of  support  a  crank-shaft  has  the  lighter 
the  webs  can  be  made  and  still  have  requisite  strength. 


Combustion  Chamber  Design 


239 


COMBUSTION    CHAMBER    DESIGN 

Another  point  of  importance  in  the  design  of  the  cylin- 
der, and  one  which  has  considerable  influence  upon  the 
power  developed,  is  the  shape  of  the  combustion  chamber. 
The  endeavor  of  designers  is  to  obtain  maximum  power 
from  a  cylinder  of  certain  proportions,  and  the  greater 
energy  obtained  without  increasing  piston  displacement 
or  fuel  consumption  the  higher  the  efficiency  of  the  motor. 
To  prevent  troubles  due  to  pre-ignition  it  is  necessary 


Fig.    88.— Aluminum   Cylinder  Pair   Casting  of  Thomas  150   Horse-Power 
Airplane  Engine  is  of  the  L  Head  Type. 

that  the  combustion  chamber  be  made  so  that  there  will 
be  no  roughness,  sharp  corners,  or  edges  of  metal  which 
may  remain  incandescent  when  heated  or  which  will  serve 
to  collect  carbon  deposits  by  providing  a  point  of  anchor- 
age. With  the  object  of  providing  an  absolutely  clean 
combustion  chamber  some  makers  use  a  separable  head 
unit  to  their  twin  cylinder  castings,  such  as  shown  at 
Fig.  87  and  Fig.  88.  These  permit  one  to  machine  the 
entire  interior  of  the  cylinder  and  combustion  chamber. 
The  relation  of  valve  location  and  combustion  chamber 
design  will  be  considered  in  proper  sequence.  These 
cylinders  are  cast  of  aluminum,  instead  of  cast  iron,  as 


240  Aviation  Engines 

is  customary,  and  are  provided  with  steel  or  cast  iron 
cylinder  liners  forced  in  the  soft  metal  casting  bores. 

BORE  AND  STROKE  RATIO 

A  question  that  has  been  a  vexed  one  and  which  has 
been  the  subject  of  considerable  controversy  is  the  proper 
proportion  of  the  bore  to  the  stroke.  The  early  gas  en- 
gines had  a  certain  well-defined  bore  to  stroke  ratio,  as 
it  was  usual  at  that  time  to  make  the  stroke  twice  as  long 
as  the  bore  was  wide,  but  this  cannot  be  done  when  high 
speed  is  desired.  "With  the  development  of  the  present- 
day  motor  the  stroke  or  piston  travel  has  been  gradually 
shortened  so  that  the  relative  proportions  of  bore  and 
stroke  have  become  nearly  equal.  Of  late  there  seems  to 
be  a  tendency  among  designers  to  return  to  the  propor- 
tions which  formerly  obtained,  and  the  stroke  is  some- 
times one  and  a  half  or  one  and  three-quarter  times  the 
bore. 

Engines  designed  for  high  speed  should  have  the  stroke 
not  much  longer  than  the  diameter  of  the  bore.  The  dis- 
advantage of  short-stroke  engines  is  that  they  will  not 
pull  well  at  low  speeds,  though  they  run  with  great  regu- 
larity and  smoothness  at  high  velocity.  The  long-stroke 
engine  is  much  superior  for  slow  speed  work,  and  it  will 
pull  steadily  and  with  increasing  power  at  low  speed. 
It  was  formerly  thought  that  such  engines  should  never 
turn  more  than  a  moderate  number  of  revolutions,  in 
order  not  to  exceed  the  safe  piston  speed  of  1.000  feet 
per  minute.  This  old  theory  or  rule  of  practice  has  been 
discarded  in  designing  high  efficiency  automobile  racing 
and  aviation  engines,  and  piston  speeds  from  2,500  to 
3,000  feet  per  minute  are  sometimes  used,  though  the 
average  is  around  2,000  feet  per  minute.  While  both 
short-  and  long-stroke  motors  have  their  advantages,  it 
would  seem  desirable  to  average  between  the  two.  That 
is  why  a  proportion  of  four  to  five  or  six  seems  to  be 
more  general  than  that  of  four  to  seven  or  eight,  which 
would  be  a  long-stroke  ratio.  Careful  analysis  of  a  num- 


Meaning  of  Piston  Speed  241 

her  of  foreign  aviation  motors  shows  that  the  average 
stroke  is  about  1.2  times  the  bore  dimensions,  though 
some  instances  were  noted  where  it  was  as  high  as  1.7 
times  the  bore. 

MEANING    OF    PISTON    SPEED 

The  factor  which  limits  the  stroke  and  makes  the 
speed  of  rotation  so  dependent  upon  the  travel  of  the 
piston  is  piston  speed.  Lubrication  is  the  main  factor 
which  determines  piston  speed,  and  'the  higher  the  rate 
of  piston  travel  the  greater  care,  must  be  taken  to  insure 
proper  oiling.  Let  us  fully  consider  what  is  meant  by 
piston  speed. 

Assume  that  a  motor  has  a  piston  travel  or  stroke  of 
six  inches,  for  the  sake  of  illustration.  It  would  take  two 
strokes  of  the  piston  to  cover  one  foot,  or  twelve  inches, 
and  as  there  are  two  strokes  to  a  revolution  it  will  be 
seen  that  this  permits  of  a  normal  speed  of  1,000  revolu- 
tions per  minute  for  an  engine  with  a  six-inch  stroke,  if 
one  does  not  exceed  1,000  feet  per  minute.  If  the  stroke 
was  only  four  inches,  a  normal  speed  of  1,500  revolutions 
per  minute  would  be  possible  without  exceeding  the  pre- 
scribed limit.  The  crank-shaft  of  a  small  engine,  having 
three-inch  stroke,  could  turn  at  a  speed  of  2,000  revolu- 
tions per  minute  without  danger  of  exceeding  the  safe 
speed  limit.  It  will  be'  seen  that  the  longer  the  stroke 
the  slower  the  speed  of  the  engine,  if  one  desires  to  keep 
the  piston  speed  within  the  bounds  as  recommended,  but 
modern  practice  allows  of  greatly  exceeding  the  speeds 
formerly  thought  best. 

ADVANTAGES    OF    OFF-SET    CYLINDERS 

Another  point  upon  which  considerable  difference  of 
opinion  exists  relates  to  the  method  of  placing  the  cylin- 
der upon  the  crank-case  —  i.e.,  whether  its  center  line 
should  be  placed  directly  over  the  center  of  the  crank- 
shaft, or  to  one  side  of  center.  The  motor  shown  at 
Fig.  90  is  an  off-set  type,  in  that  the  center  line  of  the 


242 


Aviation  Engines 


cylinder  is  a  little  to  one  side  of  the  center  of  the  crank- 
shaft. Diagrams  are  presented  at  Fig.  91  which  show 
the  advantages  of  off-set  crank-shaft  construction.  The 


Rocker  Arm -—---. 


Exhaust 


Exhaust  Pipe  -'' 


Applied  Sheet—"" 
Metal  Water  Jacket 


Steel  Cylinder-'' 


,'Laminctted  Leaf 
Spring 


^, Intake  Valve 


,.-Coirburetor 


Push  and 
Pull  Rod 


"-Cylinder 
Center  Line. 


—  -Crank  Shaft 
Center  Line 


Fig.  90. — Cross  Section  of  Austro-Daimler  Engine,  Showing  Offset  Cylinder 
Construction.    Note  Applied  Water  Jacket  and  Peculiar  Valve  Action. 

view  at  A  is  a  section  through  a  simple  motor  with  the 
conventional  cylinder  placing,  the  center  line  of  both 
crank-shaft  and  cylinder  coinciding.  The  view  at  B  shows 


Advantages  of  Offset  Cylinders 


243 


the  cylinder  placed  to  one  side  of  center  so  that  its  center 
line  is  distinct  from  that  of  the  crank-shaft  and  at  some 
distance  from  it.  The  amount  of  off-set  allowed  is  a  point 
of  contention,  the  usual  amount  being  from  fifteen  to 
twenty-five  per  cent,  of  the  stroke.  The  advantages  of 
the  off-set  are  shown  at  Fig.  91,  C.  If  the  crank  turns 


MINI 


mill 


\i//7e  of  Side 
Thrust  Against 
Cylinder  Wall, 
Which  Increases 

With  Angularity    ^ 

of  Connecting 
Rod          i 


Resistance  to  / 

Motion    Center  Line  of 
Crank 


\ 

Note  Decreased 
Side  Thrust 
Because  of  Letter 

Angle  of 
Connecting  Rod 


Center  Line  of 
Cylinder 


Fig.  91. — Diagrams  Demonstrating  Advantages  of  Offset  Crank-Shaft 

Construction. 

in  direction  of  the  arrow  there  is  a  certain  resistance  to 
motion  which  is  proportional  to  the  amount  of  energy 
exerted  by  the  engine  and  the  resistance  offered  by  the 
load.  There  are  two  thrusts  acting  against  the  cylinder 
wall  to  be  considered,  that  due  to  explosion  or  expansion 
of  the  gas,  and  that  which  resists  the  motion  of  the  piston. 
These  thrusts  may  be  represented  by  arrows,  one  which 
acts  directly  in  a  vertical  direction  on  the  piston  top,  the 


244  Aviation  Engines 

other  along  a  straight  line  through  the  center  of  the 
connecting  rod.  Between  these  two  thrusts  one  can  draw 
a  line  representing  a  resultant  force  which  serves  to  bring 
the  piston  in  forcible  contact  with  one  side  of  the  cylinder 
wall,  this  being  known  as  side  thrust.  As  shown  at  C, 
the  crank-shaft  is  at  90  degrees,  or  about  one-half  stroke, 
and  the  connecting  rod  is  at  20  degrees  angle.  The 
shorter  connecting  rod  would  increase  the  diagonal  re- 
sultant and  side  thrusts,  while  a  longer  one  would  reduce 
the  angle  of  the  connecting  rod  and  the  side  thrust  of 
the  piston  would  be  less.  With  the  off-set  construction, 
as  shown  at  D,  it  will  be  noticed  that  with  the  same  con- 
necting-rod length  as  shown  at  C  and  with  the  crank- 
shaft at  90  degrees  of  the  circle  that  the  connecting-rod 
angle  is  14  degrees  and  the  side  thrust  is  reduced  pro- 
portionately. 

Another  important  advantage  is  that  greater  efficiency 
is  obtained  from  the  explosion  with  an  off-set  crank-shaft, 
because  the  crank  is  already  inclined  when  the  piston  is 
at  top  center,  and  all  the  energy  imparted  to  the  piston 
by  the  burning  mixture  can  be  exerted  directly  into  pro- 
ducing a  useful  turning  effort.  "When  a  cylinder  is  placed 
directly  on  a  line  with  the  crank-shaft,  as  shown  at  A, 
it  will  be  evident  that  some  of  the  force  produced  by  the 
expansion  of  the  gas  will  be  exerted  in  a  direct  line  and 
until  the  crank  moves  the  crank  throw  and  connecting 
rod  are  practically  a  solid  member.  The  pressure  which 
might  be  employed  in  obtaining  useful  turning  effort  is 
wasted  by  causing  a  direct  pressure  upon  the  lower  half 
of  the  main  bearing  and  the  upper  half  of  the  crank-pin 
bushing. 

Very  good  and  easily  understood  illustrations  show- 
ing advantages  of  the  off-set  construction  are  shown  at 
E  and  F.  This  is  a  bicycle  crank-hanger.  It  is  advanced 
that  the  effort  of  the  rider  is  not  as  well  applied  when 
the  crank  is  at  position  E  as  when  it  is  at  position  F. 
Position  E  corresponds  to  the  position  of  the  parts  when 
the  cylinder  is  placed  directly  over  the  crank-shaft  center. 


Valve  Location  Practice  245 

Position  F  may  be  compared  to  the  condition  which  is 
present  when  the  off-set  cylinder  construction  is  used. 

VALVE   LOCATION    OF    VITAL   IMPORT 

It  has  often  been  said  that  a  chain  is  no  stronger  than 
its  weakest  link,  and  this  is  as  true  of  the  explosive  motor 
as  it  is  of  any  other  piece  of  mechanism.  Many  motors 
which  appeared  to  be  excellently  designed  and  which 
were  well  constructed  did  not  prove  satisfactory  because 
some  minor  detail  or  part  had  not  been  properly  consid- 
ered by  the  designer.  A  factor  having  material  bearing 
upon  the  efficiency  of  the  internal  combustion  motor  is 
the  location  of  the  valves  and  the  shape  of  the  combus- 
tion chamber  which  is  largely  influenced  by  their  placing. 
The  fundamental  consideration  of  valve  design  is  that 
the  gases  be  admitted  and  discharged  from  the  cylinder 
as  quickly  as  possible  in  order  that  the  speed  of  gas  flow 
will  not  be  impeded  and  produce  back  pressure.  This  is 
imperative  in  obtaining  satisfactory  operation  in  any 
form  of  motor.  If  the  inlet  passages  are  constricted  the 
cylinder  will  not  fill  with  explosive  mixture  promptly, 
whereas  if  the  exhaust  gases  are  not  fully  expelled  the 
parts  of  the  inert  products  of  combustion  retained  dilute 
the  fresh  charge,  making  it  slow  burning  and  causing  lost 
power  and  overheating.  When  an  engine  employs  water 
as  a  cooling  medium  this  substance  will  absorb  the  sur- 
plus heat  readily,  and  the  effects  of  overheating  are  not 
noticed  as  quickly  as  when  air-cooled  cylinders  are  em- 
ployed. Valve  sizes  have  a  decided  bearing  upon  the 
speed  of  motors  and  some  valve  locations  permit  the 
use  of  larger  members  than  do  other  positions. 

While  piston  velocity  is  an  important  factor  in  de- 
terminations of  power  output,  it  must  be  considered  from 
the  aspect  of  the  wear  produced  upon  the  various  parts, 
of  the  motor.  It  is  evident  that  engines  which  run  very 
fast,  especially  of  high  power,  must  be  under  a  greater 
strain  than  those  operating  at  lower  speeds.  The  valve- 
operating  mechanism  is  especially  susceptible  to  the  in- 


246 


Aviation  Engines 


fluence  of  rapid  movement,  and  the  slower  the  engine  the 
longer  the  parts  will  wear  and  the  more  reliable  the 
valve  action. 

As  will  be  seen  by  reference  to  the  accompanying  illus- 
tration, Fig.  92,  there  are  many  ways  in  which  valves  may 
be  placed  in  the  cylinder.  Each  method  outlined  posses- 
ses some  point  of  advantage,  because  all  of  the  types 


Fig.  92. — Diagram  Showing  Forms  of  Cylinder  Demanded  by  Different  Valve 
Placings.  A — T  Head  Type,  Valves  on  Opposite  Sides.  B — L  Head 
Cylinder,  Valves  Side  by  Side.  C — L  Head  Cylinder,  One  Valve  in  Head, 
Other  in  Pocket.  D — Inlet  Valve  Over  Exhaust  Member,  Both  in  Side 
Pocket.  E — Valve-in-the-Head  Type  with  Vertical  Valves.  F — Inclined 
Valves  Placed  to  Open  Directly  into  Combustion  Chamber. 


Valve  Location  Practice  247 

illustrated  are  used  by  reputable  automobile  manufac- 
turers. The  method  outlined  at  Fig.  92,  A,  is  widely 
used,  and  because  of  its  shape  the  cylinder  is  known  as 
the  "T"  form.  It  is  approved  for  automobile  use  for 
several  reasons,  the  most  important  being  that  large 
valves  can  be  employed  and  a  well-balanced  and  symmet- 
rical cylinder  casting  obtained.  Two  independent  cam- 
shafts are  needed,  one  operating  the  inlet  valves,  the 
other  the  exhaust  members.  The  valve-operating  mech- 
anism can  be  very  simple  in  form,  consisting  of  a  plunger 
actuated  by  the  cam  which  transmits  the  cam  motion  to 
the  valve-stem,  raising  the  valve  as  the  cam  follower 
rides  on  the  point  of  the  cam.  Piping  may  be  placed 
without  crowding,  and  larger  manifolds  can  be  fitted  than 
in  some  other  constructions.  This  has  special  value,  as 
it  permits  the  use  of  an  adequate  discharge  pipe  on  the 
exhaust  side  with  its  obvious  advantages.  This  method 
of  cylinder  construction  is  never  found  on  airplane  en- 
gines because  it  does  not  permit  of  maximum  power 
output. 

On  the  other  hand,  if  considered  from  a  viewpoint  of 
actual  heat  efficiency,  it  is  theoretically  the  worst  form  of 
combustion  chamber.  This  disadvantage  is  probably  com- 
pensated for  by  uniformity  of  expansion  of  the  cylinder 
because  of  balanced  design.  The  ignition  spark-plug  may 
be  located  directly  over  the  inlet  valve  in  the  path  of  the 
incoming  fresh  gases,  and  both  valves  may  be  easily  re- 
moved and  inspected  by  unscrewing  the  valve  caps  with- 
out taking  off  the  manifolds. 

The  valve  installation  shown  at  C  is  somewhat  un- 
usual, though  it  provides  for  the  use  of  valves  of  large 
diameter.  Easy  charging  is  insured  because  of  the  large 
inlet  valve  directly  in  the  top  of  the  cylinder.  Conditions 
may  be  reversed  if  necessary,  and  the  gases  discharged 
through  this  large  valve.  Both  methods  are  used,  though 
it  would  seem  that  the  free  exhaust  provided  by  allowing 
the  gases  to  escape  directly  from  the  combustion  chamber 
through  the  overhead  valve  to  the  exhaust  manifold 


248  Aviation  Engines 

would  make  for  more  power.  The  method  outlined  at 
Fig.  92,  F  and  at  Fig.  90  is  one  that  has  been  widely 
employed  on  large  automobile  racing  motors  where  ex- 
treme power  is  required  as  well  as  in  engines  constructed 
for  aviation  service.  The  inclination  of  the  valves  per- 
mits the  use  of  large  valves,  and  these  open  directly  into 
the  combustion  chamber.  There  are  no  pockets  to  retain 
heat  or  dead  gas,  and  free  intake  and  outlet  of  gas  is 
obtained.  This  form  is  quite  satisfactory  from  a  theo- 
retical point  of  view  because  of  the  almost  ideal  combus- 
tion chamber  form.  Some  difficulty  is  experienced,  how- 
ever, in  properly  water-jacketing  the  valve  chamber  which 
experience  has  shown  to  be  necessary  if  the  engine  is  to 
have  high  power. 

The  motor  shown  at  Fig.  92,  B  and  Fig.  88  employs 
cylinders  of  the  "L"  type.  Both  valves  are  placed  in 
a  common  extension  from  the  combustion  chamber,  and 
being  located  side  by  side  both  are  actual  from  a  com- 
mon cam-shaft.  The  inlet  and  exhaust  pipes  may  be 
placed  on  the  same  side  of  the  engine  and  a  very  com- 
pact assemblage  is  obtained,  though  this  is  optional  if 
passages  are  cored  in  the  cylinder  pairs  to  lead  the  gases 
to  opposite  sides.  The  valves  may  be  easily  removed 
if  desired,  and  the  construction  is  fairly  good  from  the 
viewpoint  of  both  foundry  man  and  machinist.  The  chief 
disadvantage  is  the  limited  area  of  the  valves  and  the 
loss  of  heat  efficiency  due  to  the  pocket.  This  form  of 
combustion  chamber,  however,  is  more  efficient  than  the 
"T"  head  construction,  though  with  the  latter  the  use  of 
larger  valves  probably  compensates  for  the  greater  heat 
loss.  It  has  been  stated  as  an  advantage  of  this  con- 
struction that  both  manifolds  can  be  placed  at  the  same 
side  of  the  engine  and  a  compact  assembly  secured.  On 
the  other  hand,  the  disadvantage  may  be  cited  that  in 
order  to  put  both  pipes  on  the  same  side  they  must  be 
of  smaller  size  than  can  be  used  when  the  valves  are 
oppositely  placed.  The  "L"  form  cylinder  is  sometimes 
made  more  efficient  if  but  one  valve  is  placed  in  the  pocket 


Valve  Location  Practice 


249 


while  the  other  is  placed  over  it.  This  construction  is 
well  shown 'at  Fig.  92,  D  and  is  found  on  Anzani  motors. 
The  method  of  valve  application  shown  at  Fig.  87  is 
an  ingenious  method  of  overcoming  some  of  the  disad- 
vantages inherent  with  valve-in-the-head  motors.  In  the 
first  place  it  is  possible  to  water-jacket  the  valves  thor- 


Rocker  Arm  Shaft 

Oil  Cap " 

Adjusting  Ball  End- 
Lock  Nu+ 


Push  Pod 


Valve  Lifter  6  ufde 
Valve.  Lifter 


Valve  Rocker  Arm 
Valve  Si-em 

Valve  Spring 
"•Valve  Cage  Nut 

Valve  Cage 

Packing  Ring 

Valve'  Cage 
.—Valve 


Cylinder 

. Connecting  Rod 

" '  Cra  n  k  •  S.ha  ft 


Fig.   93. — Sectional  View   of  Engine   Cylinder  Showing  Valve   and  Cage 

Installation. 

oughly,  which  is  difficult  to  accomplish  when  they  are 
mounted  in  cages.  The  water  circulates  directly  around 
the  walls  of  the  valve  chambers,  which  is  superior  to  a 
construction  where  separate  cages  are  used,  as  there  are 
two  thicknesses  of  metal  with  the  latter,  that  of  the  valve- 
cage  proper  and  the  wall  of  the  cylinder.  The  cooling 
medium  is  in  contact  only  with  the  outer  wall,  and  as 
there  is  always  a  loss  of  heat  conductivity  at  a  joint  it 


250 


Aviation  Engines 


is  practically  impossible  to  keep  the  exhaust  valves  and 
their  seats  at  a  uniform  temperature.  The  valves  may 
be  of  larger  size  without  the  use  of  pockets  when  seating 
directly  in  the  head.  In  fact,  they  could  be  equal  in 


B 


Fig.  94. — Diagrams  Showing  How  Gas  Enters  Cylinder  Through  Overhead 
Valves  and  Other  Types.  A — Tee  Head  Cylinder.  B — L  Head  Cylinder. 
C — Overhead  Valve. 

diameter  to  almost  half  the  bore  of  the  cylinder,  which 
provides  an  ideal  condition  of  charge  placement  and  ex- 
haust. When  valve  grinding  is  necessary  the  entire  head 
is  easily  removed  by  taking  off  six  nuts  and  loosen- 
ing inlet  manifold  connections,  which  operation  would 
be  necessary  even  if  cages  were  employed,  as  in  the 
engine  shown  at  Fig.  93. 


Valve  Location  Practice 


251 


At  Fig.  94,  A  and  B,  a  section  through  a  typical  "L"-. 
shaped  cylinder  is  depicted.  It  will  be  evident  that  where 
a  pocket  construction  is  employed,  in  addition  to  its  fac- 
ulty for  absorbing  heat,  the  passage  of  gas  would  be 
impeded.  For  example,  the  inlet  gas  rushing  in  through 
the  open  valve  would  impinge  sharply  upon  the  valve-cap 
or  combustion  head  directly  over  the  valve  and  then  must 
turn  at  a  sharp  angle  to  enter  the  combustion  chamber 


A 


Fig.  95. — Conventional  Methods  of  Operating  Internal  Combustion  Motor 

Valves. 


252 


Aviation    Engines 


and  then  at  another  sharp  angle  to  fill  the  cylinders.  The 
same  conditions  apply  to  the  exhaust  gases,  though  they 
are  reversed.  When  the  valve-in-the-head  type  of  cylin- 
der is  employed,  as  at  C,  the  only  resistance  offered  the 
gas  is  in  the  manifold.  As  far  as  the  passage  of  the 
gases  in  and  out  of  the  cylinder  is  concerned,  ideal  condi- 
tions obtain.  It  is  claimed  that  valve.-in-the-head  motors 
are  more  flexible  and  responsive  than  other  forms,  but  the 
construction  has  the  disadvantage  in  that  the  valves  must 
be  opened  through  a  rather  complicated  system  of  push 


Tig.  96. — Examples   of  Direct  Valve   Actuation  "by   Overhead   Cam-Shaft, 
A — Mercedes.     B — Hall-Scott.    C — Wisconsin. 

rods  and  rocker  arms  instead  of  the  simpler  and  direct 
plunger  which  can  be  used  with  either  the  "T"  or  "L" 
head  cylinders.  .This  is  clearly  outlined  in  the  illustra- 
tions at  Fig.  95,  where  A  shows  the  valve  in  the  head- 
operating  mechanism  necessary  if  the  cam-shaft  is  car- 
ried at  the  cylinder  base,  while  B  shows  the  most  direct 
push-rod  action  obtained  with  "T"  or  "L"  head  cylinder 
placing. 

The  objection  can  be  easily  met  by  carrying  the  cam- 
shaft above  the  cylinders  and  driving  it  by  means  of 
gearing.  The  types  of  engine  cylinders  using  this  con- 
struction are  shown  at  Fig.  96,  and  it  will  be  evident  that 
a  positive  and  direct  valve  action  is  possible  by  following 
the  construction  originated  by  the  Mercedes  (German) 


Valve  Location  Practice  253 


Fig.  97. 

CENSORED 


254  Aviation    Engines 


Fig.  98. 

CENSORED 


aviation  engine  designers  and  outlined  at  A.  The  other 
forms  at  B  and  C  are  very  clearly  adaptations  of  this 
design.  The  Hall-Scott  engine  at  Fig.  97  is  depicted  in 
part  section  and  no  trouble  will  be  experienced  in  under- 
standing the  bevel  pinion  and  gear  drive  from  the  crank- 


Concentric  Valve  Design 


255 


shaft  to  the  overhead  cam-shaft  through  a  vertical  coun- 
ter-shaft. A  very  direct  valve  action  is  used  in  the 
Duesenberg  engines,  one  of  which  is  shown  in  part  section 
at  Fig.  98.  The  valves  are -parallel  with  the  piston  top 
and  are  actuated  by  rocker  arms,  one  end  of  which  bears 
against  the  valve  stem,  and  the  other  rides  the.  cam-shaft. 


,'Main  Rocker  Arm 


Exhaust 

Valve 

Sleeve. 


Auxiliary  Rocker ' 
Arm  for  Inlet 
Valve 


Section  at  A-B 


Inlet 
Valve 
Open 


Fig.  99. — Sectional  Views  Showing  Arrangement  of  Novel  Concentric  Valve 
Arrangement  Devised  by  Panhard  for  Aerial  Engines. 

The  form  shown  at  Fig.  99  shows  an  ingenious  appli- 
cation of  the  valve-in-the-head  idea  which  permits  one 
to  obtain  large  valves.  It  has  been  used  on  some  of  the 
Panhard  aviation  engines  and  on  the  American  Aero- 
marine  power  plants.  The  inlet  passage  is  controlled 
by  the  sliding  sleeve  which  is  hollow  and  slotted  so  as 
to  permit  the  inlet  gases  to  enter  the  cylinder  through 
the  regular  type  poppet  valve  which  seats  in  the  exhaust 
sleeve.  When  the  exhaust  valve  is  operated  by  the  tap- 
pet rod  and  rocker  arm  the  intake  valve  is  also  carried 


256  Aviation  Engines 

down  with  it.  The  intake  gas  passage  is  closed,  however, 
and  the  burned  gases  are  discharged  through  the  large 
annular  passage  surrounding  the  sleeve.  When  the  inlet 
valve  leaves  its  seat  in  the  sleeve  the  passage  of  cool 
gas  around  the  sleeve  keeps  the  temperature  of  both 
valves  to  a  low  point  and  the  danger  of  warping  is  mini- 
mized. A  dome-shaped  combustion  chamber  may  be  used, 
which  is  an  ideal  form  in  conserving  heat  efficiency,  and 
as  large  values  may  be  installed  the  flow  of  both  fresh 
and  exhaust  gases  may  be  obtained  with  minimum  resist- 
ance. The  intake  valve  is  opened  by  a  small  auxiliary 
rocker  arm  which  is  lifted  when,  the  cam  follower  rides 
into  the  depression  in  the  cam  by  the  action  of  the  strong 
spring  around  the  push  rod.  .When  the  cam  follower  rides 
on  the  high  point  the  exhaust  sleeve  is  depressed  from 
its  seat  against  the  cylinder.  By  using  a  cam  having  both 
positive  and  negative  profiles,  a  single  rod  suffices  for 
both  valves  because  of  its  push  and  pull  action. 

VALVE  DESIGN  AND   CONStRTJCTION 

Valve  dimensions  are  an  important  detail  to  be  con- 
sidered and  can  be  determined  by  several  conditions, 
among  which  may  be  cited  method  of  installation,  oper- 
ating mechanism,  material  employed,  engine  speed  de- 
sired, manner  of  cylinder  cooling  and  degree  of  lift 
desired.  A  review  of  various  methods  of  valve  location 
has  shown  that  when  the  valves  are  placed  directly  in 
the  head  we  can  obtain  the  ideal  cylinder  form,  though 
larger  valves  may  be  used  if  housed  in  a  separate  pocket, 
as  afforded  by  the  "T"  head  construction.  The  method 
of  operation  has  much  to  do  with  the  size  of  the  valves. 
For  example,  if  an  automatic  inlet  valve  is  employed  it 
is  good  practice  to  limit  the  lift  and  obtain  the  required 
area  of  port  opening  by  augmenting  the  diameter.  Be- 
cause of  this  a  valve  of  the  automatic  type  is  usually 
made  twenty  per  cent,  larger  than  one  mechanically  oper- 
ated. When  both  are  actuated  by  cam  mechanism,  as  is 
now  common  practice,  they  are  usually  made  the  same 


Valve  Design  and  Construction  257 

size  and  are  interchangeable,  which  greatly  simplifies 
manufacture.  The  relation  of  valve  diameter  to  cylin- 
der bore  is  one  that  has  been  discussed  for  some  time 
by  engineers.  The  writer's  experience  would  indicate  that 
they  should  be  at  least  half  the  bore,  if  possible.  While 
the  mushroom  type  or  poppet  valve  has  become  standard 
and  is  the  most  widely  used  form  at  the  present  time, 
there  is  some  difference  of  opinion  among  designers  as 
to  the  materials  employed  and  the  angle  of  the  seat.  Most 
valves  have  a  bevel  seat,  though  some  have  a  flat  seating. 
The  flat  seat  valve  has  the  distinctive  advantage  of  pro- 
viding a  clear  opening  with  lesser  lift,  this  conducing  to 
free  gas  flow.  It  also  has  value  because  it  is  silent  in 
operation,  but  the  disadvantage  is  present  that  best  mate- 
rial and  workmanship  must  be  used  in  their  construction 
to  obtain  satisfactory  results.  As  it  can  be  made  very 
light  it  is  particularly  well  adapted  for  use  as  an  auto- 
matic inlet  valve.  Among  other  disadvantages  cited  is 
the  claim  that  it  is  more  susceptible  to  derangement,  owing 
to  the  particles  of  foreign  matter  getting  under  the  seat. 
With  a  bevel  seat  it  is  argued  that  the  foreign  matter 
would  be  more  easily  dislodged  by  the  gas  flow,  and  that 
the  valve  would  close  tighter  because  it  is  drawn  posi- 
tively against  the  bevel  seat. 

Several  methods  of  valve  construction  are  the  vogue, 
the  most  popular  form  being  the  one-piece  type;  those 
which  are  composed  of  a  head  of  one  material  and  stem 
of  another  are  seldom  used  in  airplane  engines  because 
they  are  not  reliable.  In  the  built-up  construction  the 
head  is  usually  of  high  nickel  steel  or  cast  iron,  which 
metals  possess  good  heat-resisting  qualities.  Heads  made 
of  these  materials  are  not  likely  to  warp,  scale,  or  pit, 
as  is  sometimes  the  case  when  ordinary  grades  of  ma- 
chinery steel  are  used.  The  cast-iron  head  construction 
is  not  popular  because  it  is  often  difficult  to  keep  the  head 
tight  on  the  stem.  There  is  a  slight  difference  in  ex- 
pansion ratio  between  the  head  and  the  stem,  and  as  the 
stem  is  either  screwed  or  riveted  to  the  cast-iron  head 


258 


Aviation  Engines 


the  constant  hammering  of  the  valve  against  its  seat  may 
loosen  the  joint.  As  soon  as  the  head  is  loose  on  the  stem 
the  action  of  the  valve  becomes  erratic.  The  best  practice 
is  to  machine  the  valves  from  tungsten  steel  forgings. 
This  material  has  splendid  heat-resisting  qualities  and 
will  not  pit  or  become  scored  easily.  Even  the  electri- 
cally welded  head  to  stem  types  which  are  used  in  auto- 


L/ne  rearrr 

a  -f ter  assembling 

.  375*. 0005 -- 


Fig.    100. — Showing    Clearance    Allowed    Between    Valve     Stem 
and    Valve     Stem    Guide  to  Secure  Free  Action. 

mobile  engines  are  not  looked  upon  with  favor  in  the 
aviation  engine.  Valve  stem  guides  and  valve  stems  must 
be  machined  very  accurately  to  insure  correct  action.  The 
usual  practice  in  automobile  engines  is  shown  at  Fig.  100. 

VALVE    OPERATION" 

The  methods  of  valve  operation  commonly  used  vary 
according  to  the  type  of  cylinder  construction  employed. 
In  all  cases  the  valves  are  lifted  from  their  seats  by  cam- 
actuated  mechanism.  Various  forms  of  valve-lifting  cams 
are  shown  at  Fig.  101.  As  will  be  seen,  a  cam  consists 


Valve-Lifting  Cams 


259 


of  a  circle  to  which,  a  raised,  approximately  triangular 
member  has  been  added  at  one  point.  When  the  cam 
follower  rides  on  the  circle,  as  shown  at  Fig.  1.02,  there 
is  no  difference  in  height  between  the  cam  center  and  its 
periphery  and  there  is  no  movement  of  the  plunger.  As 
soon  as  the  raised  portion  of  the  cam  strikes  the  plunger 
it  will  lift  it,  and  this  reciprocating  movement  is  trans- 
mitted to  the  valve  stem  by  suitable  mechanical  connec- 
tions. 

The  cam  forms  outlined  at  Fig.   101  are  those  com- 
monly used.     That  at  A  is  used  on  engines  where  it  is 


Fig.  101. — Forms  of  Valve-Lifting  Cams  Generally  Employed.  A — Cam 
Profile  for  Long  Dwell  and  Quick  Lift.  B— Typical  Inlet  Cam  Used 
with  Mushroom  Type  Follower.  C — Average  Form  of  Cam.  D — 
Designed  to  Give  Quick  Lift  and  Gradual  Closing. 

desired  to  obtain  a  quick  lift  arid  to  keep  the  valve  fully 
opened  as  long  as  possible.  It  is  a  noisy  form,  however, 
and  is  not  very  widely  employed.  That  at  B  is  utilized 
more  often  as  an  inlet  cam  while  the  profile  shown  at  C 
is  generally  depended  on  to  operate  exhaust  valves.  The 
cam  shown  at  D  is  a?  composite  form  which  has  some 
of  the  features  of  the  other  three  types.  It  will  give  the 
quick  opening  of  form  A,  the  gradual  closing  of  form  B, 
and  the  time  of  maximum  valve  opening  provided  by  cam 
profile  C. 

The  various  types  of  valve  plungers  used  are  shown 
at  Fig.  102.  That  shown  at  A  is  the  simplest  form,  con- 
sisting of  a  simple  cylindrical  member  having  a  rounded 
end  which  follows  the  cam  profile.  These  are  sometimes 


260 


Aviation  Engines 


made  of  square  stock  or  kept  from  rotating  by  means  of 
a  key  or  pin.  A  line  contact  is  possible  when  the  plunger 
is  kept  from  turning,  whereas  but  a  single  point  bearing 
is  obtained  when  the  plunger  is  cylindrical  and  free  to 
revolve.  The  plunger  shown  at  A  will  follow  only  cam 
profiles  which  have  gradual  lifts.  The  plunger  shown  at 
B  is  left  free  to  revolve  in  the  guide  bushing  and  is  pro- 


Fig.  102. — Showing  Principal  Types  of  Cam  Followers  which  Have  Received 

General  Application. 

vided  with  a  flat  mushroom  head  which  serves  as  a  cam 
follower.  The  type  shown  at  C  carries  a  roller  at  its 
lower  end  and  may  follow  very  irregular  cam  profiles  if 
abrupt  lifts  are  desired.  While  forms  A  and  B  are  the 
simplest,  that  outlined  at  C  in  its  various  forms  is  more 
widely  used.  Compound  plungers  are  used  on  the  Curtiss 
0X2  motors,  one  inside  the  other.  The  small  or  inner  one 
works  on  a  cam  of  conventional  design,  the  outer  plunger 
follows  a  profile  having  a  flat  spot  to  permit  of  a  pull 
rod  action  instead  of  a  push  rod  action.  All  the  methods 
in  which  levers  are  used  to  operate  valves  are  more  or 
less  noisy  because  clearance  must  be  left  between  the  valve 
stem  and  the  stop  of  the  plunger.  The  space  must  be 
taken  up  before  the  valve  will  leave  its  seat,  and  when 


Valve-Stem  Clearances 


261 


the  engine  is  operated  at  high  speeds  the  forcible  contact 
between  the  plunger  and  valve  stem  produces  a  rattling 
sound  until  the  valves  become  heated  and  expand  and  the 
stems  lengthen  out.  Clearance  must  be  left  between  the 
valve  stems  and  actuating  means.  This  clearance  is  clearly 
shown  in  Fig.  103  and  should  be  .020"  (twenty  thou- 
sandths) when  engine  is  cold.  The  amount  of  clearance 
allowed  depends  entirely  upon  the  design  of  the  engine 


Screw 


Cam  Follower 

f' Rocker 
-?'      Levers 


Lock 
•Screw 


Valve,- 
Si-em 


Fig.  103.— Diagram  Showing  Proper  Clearance  to  Allow  Between  Adjust- 
ing Screw  and  Valve  Stems  in  Hall-Scott  Aviation  Engines. 

and  length  of  valve  stem.  On  the  Curtiss  0X2  engines 
the  clearance  is  but  .010"  (ten  thousandths)  because  the 
valve  stems  are  shorter.  Too  little  clearance  will  result 
in  loss  of  power  or  misfiring  when  engine  is  hot.  Too 
much  clearance  will  not  allow  the  valve  to  open  irs  full 
amount  and  will  disturb  the  timing. 


METHODS   OF   DRIVING   CAM-SHAFT 

Two  systems  of  cam-shaft  operation  are  used.  The 
most  common  of  these  is  by  means  of  gearing  of  some 
form.  If  the  cam-shaft  is  at  right  angles  to  the  crank- 
shaft it  may  be  driven  by  worm,  spiral,  or  bevel  gearing. 


262  Aviation  Engines 

If  the  cam-shaft  is  parallel  to  the  crank-shaft,  simple  spur 
gear  or  chain  connection  may  be  used  to  turn  it.  A  typi- 
cal cam-shaft  for  an  eight-cylinder  V  engine  is  shown  at 
Fig.  104.  It  will  be  seen  that  the  sixteen  cams  are  forged 
integrally  with  the  shaft  and  that  it  is  spur-gear  driven. 
The  cam-shaft  drive  of  the  Hall-Scott  motor  is  shown  at 
Fig.  97. 

While  gearing  is  more  commonly  used,  considerable 
attention  has  -been  directed  of  late  to  silent  chains  for 
cam-shaft  operation.  The  ordinary  forms  of  block  or 
roller  chain  have  not  proven  successful  in  this  applica- 


Resr  Bearing-^ 


ter  Bearing 


Pig.  104. — Cam-Shaft  of  Thomas  Airplane  Motor  Has  Cams  Forged  Integ- 
ral.   Note  Split  Cam-Shaft  Bearings  and  Method  of  Gear  Retention.     . 

tion,  but  the  silent  chain,  which  is  in  reality  a  link  belt 
operating  over  toothed  pulleys,  has  demonstrated  its 
worth.  The  tendency  to  its  use  is  more  noted  on  foreign 
motors  than  those  of  American  design.  It  first  came  to 
public  notice  when  employed  on  the  Daimler-Knight  en- 
gine for  driving  the  small  auxiliary  crank-shafts  wrhich 
reciprocated  the  sleeve  valves.  The  advantages  cited  for 
the  application  of  chains  are,  first,  silent  operation,  which 
obtains  even  after  the  chains  have  worn  considerably; 
second,. in  designing  it  is  not  necessary  to  figure  on  main- 
taining certain  absolute  center  distances  between  the 
crank- shaft  and  cam-shaft  sprockets,  as  would  be  the  case 
if  conventional  forms  of  gearing  were  used.  On  some 
forms  of  motor  employing  gears,  three  and  even  four 


Valve  Springs  263 

members  are  needed  to  turn  the  cam-shaft.  With  a  chain 
drive  but  two  sprockets  are  necessary,  the  chain  forming 
a  flexible  connection  which  permits  the  driving  and  driven 
members  to  be  placed  at  any  distance  apart  that  the 
exigencies  of  the  design  demand.  When  chains  are  used 
it  is  advised  that  some  means  for  compensating  chain 
slack  be  provided,  or  the  valve  timing  will  lag  when 
chains  are  worn.  Many  combination  drives  may  be 
worked  out  with  chains  that  would  not  be  possible  with 
other  forms  of  gearing.  Direct  gear  drive  is  favored  at 
the  present  time  by  airplane  engine  designers  because  they 
are  the  most  certain  and  positive  means,  even  when  a 
number  of  gears  must  be  used  as  intermediate  drive 
members.  With  overhead  cam-shafts,  bevel  gears  work 
out  very  well  in  practice,  as  in  the  Hall-Scott  motors  and 
others  of  that  type. 

VALVE    SPRINGS 

Another  consideration  of  importance  is  the  use  of 
proper  valve-springs,  and  particular  care  should  be  taken 
with  those  of  automatic  valves.  The  spring  must  be  weak 
enough  to  allow  the  valve  to  open  when  the  suction  is 
light,  and  must  be  of  sufficient  strength  to  close  it  in 
time  at  high  speeds.  It  should  be  made  as  large  as  pos- 
sible in  diameter  and  with  a  large  number  of  convolutions, 
in  order  that  fatigue  of  the  metal  be  obviated,  and  it  is 
imperative  that  all  springs  be  of  the  same  strength  when 
used  on  a  multiple-cylinder  engine.  Practically  all  valves 
used  to  control  the  gas  flow  in  airplane  engines  are  me- 
chanically operated.  On  the  exhaust  valve  the  spring 
must  be  strong  enough  so  that  the  valve  will  not  be  sucked 
in  on  the  inlet  stroke.  It  should  be  borne  in  mind  that 
if  the  spring  is  too  strong  a  strain  will  be  imposed  on 
the  valve-operating  mechanism,  and  a  hammering  action 
produced  which  may  cause  deformation  of  the  valve- seat. 
Only  pressure  enough  to  insure  that  the  operating  mech- 
anism will  follow  the  cam  is  required.  It  is  common 
practice  to  make  the  inlet  and  exhaust  valve  springs  of 


264 


Aviation  Engines 


the  same  tension  when  the  valves  are  of  the  same  size 
and  both  mechanically  operated.  This  is  done  merely  to 
simplify  manufacture  and  not  because  it  is  necessary  for 


Sparh  Plug 


Cranks 

0  Derating 
Sleeves 


Outer  Sleeve 


ner  Sleeve 


Fig.  105. — Section  Through  Cylinder  of  Knight  Motor,  Showing  Important 
Parts  of  Valve  Motion. 

the  inlet  valve-spring  to  be  as  strong  as  the  other.  Valve 
springs  of  the  helical  coil  type  are  generally  used,  though 
torsion  or  "scissors"  springs  and  laminated  or  single- 
leaf  springs  are  also  utilized  in  special  applications.  Two 


Valve  Springs 


265 


springs  are  used  on  each  valve  in  some  valve-in-the-head 
types;  a  spring  of  small  pitch  diameter  inside  the  regular 
valve-spring  and  concentric  with  it.  Its  function  is  to 


.•Exhaust 


Intake 


Spark  Plug 


..-Water 
Space 


Piston—- 


Intake  Stroke-Intake  Ports  Open 


Compression  Stroke  -All  Ports  Closed 


Firing  Stroke -All  Ports  Closed 


Exhaust  Stroke -Exhaust  Ports  Open 


Fig.  106. — Diagrams  Showing  Knight  Sleeve  Valve  Action. 

keep  the  valve  from  falling  into  the  cylinder  in  event  of 
breakage  of  the  main  spring  in  some  cases,  and  to  provide 
a  stronger  return  action  in  others. 


266  ,>  Aviation  Engines 

KNIGHT   SLIDE   VALVE    MOTOR 

The  sectional  view  through  the  cylinder  at  Fig.  105 
shows  the  Knight  sliding  sleeves  and  their  actuating 
means  very  clearly.  The  diagrams  at  Fig.  106  show 
graphically  the  sleeve  movements  and  their  relation  to 
the  crank-shaft  and  piston  travel.  The  action  may  be 
summed  up  as  follows:  The  inlet  port  begins  to  open 
when  the  lower  edge  of  .the  opening  of  the  outside  sleeve 
which  is  moving  down  passes  the  top  of  the  slot  in  the 
inner  member  also  moving  downwardly.  The  inlet  port 
is  closed  when  the.  lower  edge  of  the  slot  in  the  inner 
sleeve  which  is  moving  up  passes  the  top  edge  of  the  port 
in  the  outer  sleeve  which  is  also  moving  toward  the  top 
of  the  cylinder.  The  inlet  opening  extends  over  two  hun- 
dred degrees  of  crank  motion.  The  exhaust  port  is  un- 
covered slightly  when  the  lower  edge  of  the  port  in  the 
inner  sleeve  which  is  moving  down  passes  the  lower  edge 
of  the  portion  of  the  cylinder  head  which  protrudes  in 
the  cylinder.  When  the  top  of  the  port  in  the  outer  sleeve 
traveling  toward  the  bottom  of  the  cylinder  passes  the 
lower  edge  of  the  slot  in  the  cylinder  wall  the  exhaust 
passage  is  closed.  The  exhaust  opening  extends  over  a 
period  corresponding  to  about  two  hundred  and  forty 
degrees  of  crank  motion.  The  Knight  motor  has  not  been 
applied  to  aircraft  to  the  writer's  knowledge,  but  an 
eight-cylinder  Vee  design  that  might  be  useful  in  that 
•connection  if  lightened  is  shown  at  Fig.  107.  The  main 
object  is  to  show  that  the  Knight  valve  action  is  the  only 
other  besides  the  mushroom  or  poppet  valve  that  has  been 
applied  successfully  to  high  speed  gasoline  engines. 

VALVE    TIMING 

It  is  in  valve  timing  that  the  greatest  difference  of 
opinion  prevails  among  engineers,  and  it  is  rare  that  one 
will  see  the  same  formula  in  different  motors.  It  is  true 
that  the  same  timing  could  not  be  used  with  motors  of 


Valve-Timing  Practice 


267 


different  construction,  as  there  are  many  factors  which 
determine  the  amount  of  lead  to  be  given  to  the  valves. 
The  most  important  of  these  is  the  relative  size  of  the 
valve  to  the  cylinder  bore,  the  speed  of  rotation  it  is 


•Priming  Cups  -N 


Cylinder  Oi 


tt.T.Coil* 


Wiring  Header^          \ 
Junk  Ring,         \  \ 


Cylinder       \ 
Head,       ' 


,  \ — Hot  A  ir  Conn 
toCarburetor 


Piston-"' 

Ex.  Pipe,     s       /' 

Cylinder-^ ""  /    , 

Outer  Sleeve   • 
Inner  Sleeve-' 
Conn.  Rod-'  — 
Oil.By-pass  Pody  Valve'j' 
Mam  Bearing'  Oil  Lead 


\~Long  Ecc.  Shaft  Rod 
'•Short Ecc.Shaft  'Rod 
Eccentric  Shafts 

**"-•  Crank-Shaft  with 
Counter-weight 


Drain  Plug-"" 


i.C.tUtSTROM    M.y. 


Fig.  107. — Cross  Sectional  View  of  Knight  Type  Eight  Cylinder  V  Engine. 


desired  to  obtain,  the  fuel  efficiency,  the  location  of  the 
valves,  and  other  factors  too  numerous  to  mention. 

Most  of  the  readers  should  be  familiar  with  the  cycle 
of  operation  of  the  internal  combustion  motor  of  the 
four-stroke  type,  and  it  seems  unnecessary  to  go  into 
detail  except  to  present  a  review.  The  first  stroke  of  the 
piston  is  one  in  which  a  charge  of  gas  is  taken  into  the 


268  Aviation  Engines 

motor;  the  second  stroke,  which  is  in  reverse  direction 
to  the  first,  is  a  compression  stroke,  at  the  end  of  which 
the  spark  takes  place,  exploding  the  charge  and  driving 
the  piston  down  on  the  third  or  expansion  stroke,  which 
is  in  the  same  direction  as  the  intake  stroke,  and  finally, 
after  the  piston  has  nearly  reached  the  end  of  this  stroke, 
another  valve  opens  to  allow  the  burned  gases  to  escape, 
and  remains  open  until  the  piston  has  reached  the  end 
of  the  fourth  stroke  and  is  in  a  position  to  begin  the 
series  over  again.  The  ends  of  the  strokes  are  reached 
when  the  piston  comes  to  a  stop  at  either  top  or  bottom 
of  the  cylinder  and  reverses  its  motion.  That  point  is 
known  as  a  center,  and  there  are  two  for  each  cylinder, 
top  and  bottom  centers,  -respectively. 

All  circles  may  be  divided  into  360  parts,  each  of 
which  is  known  as  a  degree,  and,  in  tnrn,  each  of  these 
degrees  may  be  again  divided  into  minutes  and  seconds, 
though  we  need  not  concern  ourselves  with  anything  less 
than  the  degree.  Each  stroke  of  the  piston  represents 
180  degrees  travel  of  the  crank,  because  two  strokes  rep- 
resent one  complete  revolution  of  three  hundred  and  sixty 
degrees.  The  top  and  bottom  centers  are  therefore  sep- 
arated by  180  degrees.  Theoretically  each  phase  of  a 
four-cycle  engine  begins  and  ends  at  a  center,  though  in 
actual  practice  the  inertia  or  movement  of  the  gases 
makes  it  necessary  to  allow  a  lead  or  lag  to  the  valve,  as 
the  case  may  be.  If  a  valve  opens  before  a  center,  the 
distance  is  called  "lead";  if  it  closes  after  a  center,  this 
distance  is  known  as  "lag."  The  profile  of  the  cams 
ordinarily  used  to  open  or  close  the  valves  represents  a 
considerable  time  in  relation  to  the  180  degrees  of  the 
crank-shaft  travel,  and  the  area  of  the  passages  through 
which  the  gases  are  admitted  or  exhausted  is  quite  small 
owing  to  the  necessity  of  having  to  open  or  close  the 
valves  at  stated  times;  therefore,  to  open  an  adequately 
large  passage  for  the  gases  it  is  necessary  to  open  the 
valves  earlier  and  close  them  later  than  at  centers. 
That  advancing  the  opening  of  the  exhaust  valve  was 


Valve-Timing  Practice  269 

of  value  was  discovered  on  the  early  motors  and  is  ex- 
plained by  the  necessity  of  releasing  a  large  amount  of 
gas,  the  volume  of  which  has  been  greatly  raised  by  the 
heat  of  combustion.  When  the  inlet  valves  were  mechan- 
ically operated  it  was  found  that  allowing  them  to  lag 
at  closing  enabled  the  inspiration  of  a  greater  volume  of 
gas.  Disregarding  the  inertia  or  flow  of  the  gases,  open- 
ing the  exhaust  at  center  would  enable  one  to  obtain  full 
value  of  the  expanding  gases  the  entire  length  of  the 
piston  stroke,  and  it  would  not  be  necessary  to  keep  the 
valve  open  after  the  top  center,  as  the  reverse  stroke 
would  produce  a  suction  effect  which  might  draw  some 
of  the  inert  charge  back  into  the  cylinder.  On  the  other 
hand,  giving  full  consideration  to  the  inertia  of  the  gas, 
opening  the  valve  before  center  is  reached  will  provide 
for  quick  expulsion  of  the  gases,  which  have  sufficient 
velocity  at  the  end  of  the  stroke,  so  that  if  the  valve  is 
allowed  to  remain  open  a  little  longer,  the  amount  of  lag 
varying  with  the  opinions  of  the  designer,  the  cylinder 
is  cleared  in  a  more  thorough  manner. 

BLOWING    BACK 

When  the  factor  of  retarded  opening  is  considered 
without  reckoning  the  inertia  of  the  gases,  -it  would 
appear  that  if  the  valve  were  allowed  to  remain  open 
after  center  had  passed,  say,  on  the  closing  of  the  inlet, 
the  piston,  having  reversed  its  motion,  would  have  the 
effect  of  expelling  part  of  the  fresh  charge  through  the 
still  open  valve  as  it  passed  inward  at  its  compression 
stroke.  This  effect  is  called  blowing  back,  and  is  often 
noted  with  motors  where  the  valve  settings  are  not  ab- 
solutely correct,  or  where  the  valve-springs  or  seats  are 
defective  and  prevent  proper  closing. 

This  factor  is  not  of  as  much  import  as  might  appear, 
as  on  closer  consideration  it  will  be  seen  that  the  move- 
ment of  the  piston  as  the  crank  reaches  either  end  of  the 
stroke  is  less  per  degree  of  angular  movement  than  it 
is  when  the  angle  of  the  connecting  rod  is  greater.  Then, 


270  Aviation  Engines 

again,  a  certain  length  of  time  is  required  for  the  reversal 
of  motion  of  the  piston,  during  which  time  the  crank  is 
in  motion  but  the  piston  practically  at  a  standstill.  If  the 
valves  are  allowed  to  remain  open  during  this  period, 
the  passage  of  the  gas  in  or  out  of  the  cylinder  will  be 
by  its  own  momentum. 

LEAD   GIVEN   EXHAUST  VALVE 

The  faster  a  motor  turns,  all  other  things  being  equal, 
the  greater  the  amount  of  lead  or  advance  it  is  necessary 
to  give  the  opening  of  the  exhaust  valve.  It  is  self-evi- 
dent truth  that  if  the  speed  of  a  motor  is  doubled  it 
travels  twice  as  many  degrees  in  the  time  necessary  to 
lower  the  pressure.  As  most  designers  are  cognizant  of 
this  fact,  the  valves  are  proportioned  accordingly.  It  is 
well  to  consider  in  this  respect  that  the  cam  profile  has 
much  to  do  with  the  manner  in  wThich  the  valve  is  opened ; 
that  is,  the  lift  may  be  abrupt  and  the  gas  allowed  to 
escape  in  a  body,  or  the  opening  may  be  gradual,  the 
gas  issuing  from  the  cylinder  in  thin  streams.  An  analogy 
may  be  made  with  the  opening  of  any  bottle  which  con- 
tains liquid  highly  carbonated.  If  the  cork  is  removed 
suddenly  the  gas  escapes  with  a  loud  pop,  but,  on  the 
other  hand,  if  the  bottle  is  uncorked  gradually,  the  gas 
escapes  from  the  receptacle  in  thin  streams  around  the 
cork,  and  passage  of  the  gases  to  the  air  is  accomplished 
without  noise.  While  the  second  plan  is  not  harsh,  it 
is  slower  than  the  former,  as  must  be  evident. 

EXHAUST   CLOSING,    INLET   OPENING 

A  point  which  has  been  much  discussed  by  engineers 
is  the  proper  relation  of  the  closing  of  the  exhaust  valve 
and  the  opening  of  the  inlet.  Theoretically  they  should 
succeed  each  other,  the  exhaust  closing  at  upper  dead 
center  and  the  inlet  opening  immediately  afterward.  The 
reason  why  a  certain  amount  of  lag  is  given  the  exhaust 
closing  in  practice  is  that  the  piston  cannot  drive  the 


Valve-Timing  Practice  271 

gases  out  of  the  cylinder  unless  they  are  compressed  to 
a  degree  in  excess  of  that  existing  in  the  manifold  or 
passages,  and  while  toward  the  end  of  the  stroke  this 
pressure  may  be  feeble,  it  is  nevertheless  indispensable. 
At  the  end  of  the  piston's  stroke,  as  marked  by  the  upper 
dead  center,  this  compression  still  exists,  no  matter  how 
little  it  may  be,  so  that  if  the  exhaust  valve  is  closed  and 
the  inlet  opened  immediately  afterward,  the  pressure 
which  exists  in  the  cylinder  may  retard  the  entrance  of 
the  fresh  gas  and  a  certain  portion  of  the  inert  gas  may 
penetrate  into  the  manifold.  As  the  piston  immediately 
begins  to  aspirate,  this  may  not  be  serious,  but  as  these 
gases  are  drawn  back  into  the  cylinder  the  fresh  charge 
will  be  diluted  and  weakened  in  value.  If  the  spark-pltig 
is  in  a  pocket,  the  points  may  be  surrounded  by  this  weak 
gas,  and  the  explosion  will  not  be  nearly  as  energetic  as 
when  the  ignition  spark  takes  place  in  pure  mixture. 

It  is  a  well-known  fact  that  the  exhaust  valve  should 
close  after  dead  center  and  that  a  certain  amount  of  lag 
should  be  given  to  opening,  of  the  inlet.  The  lag  given 
the  closing  of  the  exhaust  valve  should  not  be  as  great 
as  that  given  the  closing  of  the  inlet  valve.  Assuming 
that  the  excess  pressure  of  the  exhaust  will  equal  the 
depression  during  aspiration,  the  time  necessary  to  com- 
plete the  emptying  of  the  cylinder  will  be  proportional 
to  the  volume  of  the  gas  within  it.  At  the  end  of  the 
suction  stroke  the  volume  of  gas  contained  in  the  cylinder 
is  equal  to  the  cylindrical  volume  plus  the  space  of  the 
combustion  chamber.  At  the  end  of  the  exhaust  stroke 
the  volume  is  but  that  of  the  dead  space,  and  from  one- 
third  to  one-fifth  its  volume  before  compression.  While 
it  is  natural  to  assume  that  this  excess  of  burned  gas 
will  escape  faster  than  the  fresh  gas  will  enter  the  cylin- 
der, it  will  be  seen  that  if  the  inlet  valve  were  allowed 
to  lag  twenty  degrees,  the  exhaust  valve  lag  need  not  be 
more  than  five  degrees,  providing  that  the  capacity  of 
the  combustion  chamber  was  such  that  the  gases  occupied 
one-quarter  of  their  former  volume. 


272  Aviation  Engines 

It  is  evident  that  no  absolute  rule  can  be  given,  as 
back  pressure  will  vary  with  the  design  of  the  valve 
passages,  the  manifolds,  and  the  construction  of  the 
muffler.  The  more  direct  the  opening,  the  sooner  the 
valve  can  be  closed  and  the  better  the  cylinder  cleared. 
Ten  degrees  represent  an  appreciable  angle  of  the  crank, 
and  the  time  required  for  the  crank  to  cover  this  angular 
motion  is  not  inconsiderable  and  an  important  quantity  of 
the  exhaust  may  escape,  but  the  piston  is  very  close  to 
the  dead  center  after  the  distance  has  been  covered. 

Before  the  inlet  valve  opens  there  should  be  a  certain 
depression  in  the  cylinder,  and  considerable  lag  may  be 
allowed  before  the  depression  is  appreciable.  So  far  as 
the  volume  of  fresh  gas  introduced  during  the  admission 
stroke  is  concerned,  this  is  determined  by  the  displace- 
ment of  the  piston  between  the  point  where  the  inlet  valve 
opens  and  the  point  of  closing,  assuming  that  sufficient 
gas  has  been  inspired  so  that  an  equilibrium  of  pressure 
has  been  established  between  the  interior  of  the  cylinder 
and  the  outer  air.  The  point  of  inlet  opening  varies  with 
different  motors.  It  would  appear  that  a  fair  amount  of 
lag  would  be  fifteen  degrees  past  top  center  for  the  inlet 
opening,  as  a  certain  depression  will  exist  in  the  cylinder, 
assuming  that  the  exhaust  valve  has  closed  five  or  ten 
degrees  after  center,  and  at  the  same  time  the  piston  has 
not  gone  down  far  enough  on  its  stroke  to  materially 
decrease  the  amount  of  gas  which  will  be  taken  into  the 
cylinder. 

CLOSING  THE  INLET  VALVE 

As  in  the  case  with  the  other  points  of  opening  and 
closing,  there  is  a  wide  diversity  of  practice  as  relates 
to  closing  the  inlet  valve.  Some  of  the  designers  close 
this  exactly  at  bottom  center,  but  this  practice  cannot 
be  commended,  as  there  is  a  considerable  portion  of  time, 
at  least  ten  or  fifteen  degrees  angular  motion  of  the  crank, 
before  the  piston  will  commence  to  travel  to  any  extent 
on  its  compression  stroke.  The  gases  rushing  into  the 


Valve-Timing  Practice  27  B 

cylinder  have  considerable  velocity,  and  unless  an  equi- 
librium is  obtained  between  the  pressure  inside  and  that 
of  the  atmosphere  outside,  they  will  continue  to  rush  into 
the  cylinder  even  after  the  Diston  ceases  to  exert  any 
suction  effect. 

For  this  reason,  if  the  valve  is  closed  exactly  on  cen- 
ter, a  full  charge  may  not  be  inspired  into  the  cylinder, 
though  if  the  time  of-  closing  is  delayed,  this  momentum 
or  inertia  of  the  gas  will  be  enough  to  insure  that  a 
maximum  charge  is  taken  into  the  cylinder.  The  writer 
considers  that  nothing  will  be  gained  if  the  valve  is  al- 
lowed to  remain  open  longer  than  twenty  degrees,  and  an 
analysis  of  practice  in  this  respect  would  seem  to  confirm 
this  opinion.  From  that  point  in  the  crank  movement 
the  piston  travel  increases  and  the  compressive  effect  is 
appreciable,  and  it  would  appear  that  a  considerable  pro- 
portion of  the  charge  might  be  exhausted  into  the  mani- 
fold and  carburetor  if  the  valve  were  allowed  to  remain 
open  beyond  a  point  corresponding  to  twenty  degrees 
angular  movement  of  the  crank. 

TIME    OF   IGNITION 

In  this  country  engineers  unite  in  providing  a  vari- 
able time  of  ignition,  though  abroad  some  difference  of 
opinion  is  noted  on  this  point.  The  practice  of  advanc- 
ing the  time  of  ignition,  when  affected  electrically,  was 
severely  condemned  by  early  makers,  these  maintaining 
that  it  was  necessary  because  of  insufficient  heat  and 
volume  of  the  spark,  and  it  was  thought  that  advancing 
ignition  was  injurious.  The  engineers  of  to-day  appre- 
ciate the  fact  that  the  heat  of  the  electric  spark,  espe- 
cially when  from  a  mechanical  generator  of  electrical 
energy,  is  the  only  means  by  which  we  can  obtain  prac- 
tically instantaneous  explosion,  as  required  by  the  opera- 
tion of  motors  at  high  speeds,  and  for  the  combustion 
of  large  volumes  of  gas. 

It  is   apparent  that   a  motor  with   a  fixed   point   of 


274 


Aviation  Engines 


ignition  is  not  as  desirable,  in  every  way,  as  one  in  which 
the  ignition  can  be  advanced  to  best  meet  different  re- 
quirements, and  the  writer  does  not  readily  perceive  any 


*5  Position  of  No.  I  Cylinder  Cams 

when  No.  I  Piston  is  on  top  dead  center 


Part 

Diagram  of  Gears  in  Hall-Scott- 
Type  A-5  Aviation  Motor 

'Exhaust  Closed 


Part-  B 


Magneto  \ 

fully 

Advanced 


<sv^        ,'ExhaustC. 

Vx*"""        L7~jk\ ""V.         ^ 


Intake  Closed' 


'Exhaust- 
Open 


Section  thru  Cam  Shaft 

Housing  Showing  position  of 

Cams.when  Exhaust  Valve  is  Closed 

Note  on  Chart  that  Crank-Shaft 
is  10° past  top  center  when 
Exhaust  Valve. is  closed 


Fig.  108.— Diagrams  Explaining  Valve  and  Ignition  Timing  of  Hall-Scott 

Aviation  Engine. 

advantage  outside  of  simplicity  of  control  in  establishing 
a  fixed  point  of  ignition.  In  fact,  there  seems  to  be  some 
difference  of  opinion  among  those  designers  who  favor 


Ignition  Timing 


275 


fixed  ignition,  and  in  one  case  this  is  located  forty-three 
degrees  ahead  of  center,  and  in  another  motor  the  point 
is  fixed  at  twenty  degrees,  so  that  it  may  be  said  that 
this  will  vary  as  much  as  one  hundred  per  cent,  in  various 
forms.  This  point  will  vary  with  different  methods  of 


Dead  Center 
1*6 


Fig.  109. — Timing  Diagram  of  Typical  Six-Cylinder  Engine. 

ignition,  as  well  as  the  location  of  the  spark-plug  or 
igniter.  For  the  sake  of  simplicity,  most  airplane  en- 
gines use  set  spark;  if  an  advancing  and  retarding  mech- 
anism is  fitted,  it  is  only  to  facilitate  starting,  as  the 
spark  is  kept  advanced  while  in  flight,  and  control  is  by 
throttle  alone. 

It  is  obvious  by  consideration  of  the  foregoing  that 
there  can  be  no  arbitrary  rules  established  for  timing, 


276 


Aviation  Engines 


because  of  the  many  conditions  which  determine  the  best 
times  for  opening  and  closing  the  valves.  It  is  customary 
to  try  various  settings  when  a  new  motor  is  designed 
until  the  most  satisfactory  points  are  determined,  and 
the  setting  which  will  be  very  suitable  for  one  motor  is 
not  always  right  for  one  of  different  design.  The  timing 


Fig.  110. — Timing  Diagram  of  Typical  Eight-Cylinder  V  Engine. 

diagram  shown  at  Fig.  108  applies  to  the  Hall- Scott 
engine,  and  may  be  considered  typical.  It  should  be 
easily  followed  in  view  of  the  very  complete  explanation 
given  in  preceding  pages.  Another  six-cylinder  engine 
diagram  is  shown  at  Fig.  109,  and  an  eight-cylinder  tim- 
ing diagram  is  shown  at  Fig.  110.  In  timing  automobile 
engines  no  trouble  is  experienced,  because  timing  marks 


How  an  Engine  is  Timed  277 

are  always  indicated  on  the  engine  fly-wheel  register  with 
an  indicating  trammel  on  the  ^crank-case.  To  time  an 
airplane  engine  accurately,  as  is  necessary  to  test  for  a 
suspected  cam-shaft  defect,  a  timing  disc  of  aluminum  is 
attached  to  the  crank-shaft  which  has  the  timing  marks 
indicated  thereon.  If  the  disc  is  made  10  or  12  inches 
in  diameter,  it  may  be  divided  into  degrees  without 
difficulty. 

HOW    AN    ENGINE    IS    TIMED 

In  timing  a  motor  from  the  marks  on  the  timing  disc 
rim  it  is  necessary  to  regulate  the  valves  of  but  one 
cylinder  at  a  time.  Assuming  that  the  disc  is  revolving 
in  the  direction  of  engine  rotation,  and  that  the  firing 
order  of  the  cylinders  is  1-3-4-2,  the  operation  of  timing 
would  be  carried  on  as  follows:  The  crank-shaft  would 
be  revolved  until  the  line  marked  "Exhaust  opens  1  and 
4"  registered  with  the  trammel  on  the  motor  bed.  At  this 
point  the  exhaust-valve  of  either  cylinder  No.  1  or  No.  4 
should  begin  to  open.  This  can  be  easily  determined  by 
noting  which  of  these  cylinders  holds  the  compressed 
charge  ready  for  ignition.  Assuming  that  the  spark  has 
occurred  in  cylinder  No.  1,  then  when  the  fly-wheel  is 
turned  from  the  position  to  that  in  which  the  line  marked 
"Exhaust  opens  1  and  4"  coincides  with  the  trammel 
point,  the  valve-plunger  under  the  exhaust-valve  of  cylin- 
der No.  1  should  be  adjusted  in  such  a  way  that  there  is 
no  clearance  between  it  and  the  valve  stem.  Further 
movement  of  the  wheel  in  the  same  direction  should  pro- 
duce a  lift  of  the  exhaust  valve.  The  disc  is  turned  about 
two  hundred  and  twenty-five  degrees,  or  a  little  less  than 
three-quarters  of  a  revolution;  then  the  line  marked 
"Exhaust  closes  1  and  4"  will  register  with  the  trammel 
point.  At  this  period  the  valve-plunger  and  the  valve- 
stem  should  separate  and  a  certain  amount  of  clearance 
obtain  between  them.  The  next  cylinder  to  time  would 
be  No.  3.  The  crank-shaft  is  rotated  until  mark  "Exhaust 
opens  2  and  3"  comes  in  line  with  the  trammel.  At  this 


278  Aviation  Engines 

point  the  exhaust  valve  of  cylinder  No.  3  should  be  just 
about  opening.  The  closing  is  determined  by  rotating  the 
shaft  until  the  line  "  Exhaust  closes  2  and  3"  comes 
under  the  trammel. 

This  operation  is  carried  on  with  all  the  cylinders, 
it  being  well  to  remember  -that  but  one  cylinder  is  work- 
ing at  a  time  and  that  a  half -revolution  of  the  fly-wheel 
corresponds  to  a  full  working  stroke  of  all  the  cylinders, 
and  that  while  one  is  exhausting  the  others  are  respec- 
tively taking  in  a  new  charge,  compressing  and  exploding. 
For  instance,  if  cylinder  No.  1  has  just  completed  its 
power-stroke,  the  piston  in  cylinder  No.  3  has  reached 
the  point  where  the  gas  may  be  ignited  to  advantage. 
The  piston  of  cylinder  No.  4,  which  is  next  to  fire,  is  at 
the  bottom  of  its  stroke  and  will  have  inspired  a  charge, 
while  cylinder  No.  2,  which  is  the  last  to  fire,  will  have 
just  finished  expelling  a  charge  of  burned  gas,  and  will 
be  starting  the  intake  stroke.  This  timing  relates  to  a 
four-cylinder  engine  in  order  to  simplify  the  explanation. 
The  timing  instructions  given  apply  only  to  the  conven- 
tional motor  types.  Eotary  cylinder  engines,  especially 
the  Gnome  "monosoupape,"  have  a  distinctive  valve 
timing  on  account  of  the  peculiarities  of  design. 

GNOME  "MONOSOUPAPE"  VALVE  TIMING 

In  the  present  design  of  the  Gnome  motor,  a  cycle  of 
operations  somewhat  different  from  that  employed  in  the 
ordinary  four-cycle  engine  is  made  use  of,  says  a  writer 
in  "The  Automobile,"  in  describing  the  action  of  this 
power-plant.  This  cycle  does  away  with  the  need  for  the 
usual  inlet  valve  and  makes  the  engine  operable  with  only 
a  single  valve,  hence  the  name  mono  soup  ape,  or  "  single- 
valve.  "  The  cycle  is  as  follows:  A  charge  being  com- 
pressed in  the  outer  end  of  the  cylinder  or  combustion 
chamber,  it  is  ignited  by  a  spark  produced  by  the  spark- 
plug located  in  the  side  of  this  chamber,  and  the  burning 
charge  expands  as  the  piston*  moves  down  in  the  cylinder 
while  the  latter  revolves  around  the  crank-shaft.  When 


Gnome  Monosoupape  Timing  279 

the  piston  is  about  half-way  down  on  the  power  stroke, 
the  exhaust  valve,  which  is  located  in  the  center  of  the 
cylinder-head,  is  mechanically  opened,  and  during  the 
following  upstroke  of  the  piston  the  burnt  gases  are 
expelled  from  the  cylinder  through  the  exhaust  valve 
directly  into  the  atmosphere. 

Instead  of  closing  at  the  end  of  the  exhaust  stroke, 
or  a  few  degrees  thereafter,  the  exhaust  valve  is  held 
open  for  about  two-thirds  of  the  following  inlet  stroke 
of  the  piston,  with  the  result  that  fresh  air  is  drawn 
through  the  exhaust  valve  into  the  cylinder.  "When  the 
cylinder  is  still  65  degrees  from  the  end  of  the  inlet  half- 
revolution,  the  exhaust  valve  closes.  As  no  more  air 
can  get  into  the  cylinder,  and  as  the  piston  continues  to 
move  inwardly,  it  is  obvious  that  a  partial  vacuum  is 
formed. 

When  the  cylinder  approaches  within  20  degrees  of 
the  end  of  the  inlet  half -re  volution  a  series  of  small 
inlet  ports  all  around  the  circumference  of  the  cylinder 
wall  is  uncovered  by  the  top  edge  of  the  piston,  whereby 
the  combustion  chamber  is  placed  in  communication  with 
the  crank  chamber.  As  the  pressure  in  the  crank  chamber 
is  substantially  atmospheric  and  that  in  the  combustion 
chamber  is  below  atmospheric,  there  results  a  suction 
effect  which  causes  the  air  from  the  crank  chamber  to 
flow  into  the  combustion  chamber.  The  air  in  the  crank 
chamber  is  heavily  charged  with  gasoline  vapor,  which 
is  due  to  the  fact  that  a  spray  nozzle  connected  with  the 
gasoline  supply  tank  is  located  inside  the  chamber.  The 
proportion  of  gasoline  vapor  in  the  air  in  the  crank 
chamber  is  several  times  as  great  as  in  the  ordinary 
combustible  mixture  drawn  from  a  carburetor  into  the 
cylinder.  This  extra-rich  mixture  is  diluted  in  the  com- 
bustion chamber  with  the  air  which  entered  it  through 
the  exhaust  valve  during  the  first  part  of  the  inlet  stroke, 
thus  forming  a  mixture  of  the  proper  proportion  for 
complete  combustion. 

The  inlet  ports  in  the  cylinder  wall  remain  open  until 


280  Aviation  Engines 

20  degrees  of  the  compression  half-revolution  has  been 
completed,  and  from  that  moment  to  near  the  end  of  the 
compression  stroke .  the  gases  are  compressed  in  the 
cylinder.  Near  the  end  of  the  stroke  ignition  takes  place 
and  this  completes  the  cycle. 

The  exact  timing  of  the  different  phases  of  the  cycle 
is  shown  in  the  diagram  at  Fig.  111.  It  will  be  seen  that 
ignition  occurs  substantially  20  degrees  ahead  of  the 
outer  dead  center,  and  expansion  of  the  burning  gases 
continues  until  85  degrees  past  the  outer  dead  center, 
when  the  piston  is  a  little  past  half-stroke.  Then  the 
exhaust-valve  opens  and  remains  open  for  somewhat 
more  than  a  complete  revolution  of  the  cylinders,  or,  to 
be  exact,  for  390  degrees  of  cylinder  travel,  until  115 
degrees  past  the  top  dead  center  on  the  second  revolution. 
Then  for  45  degrees  of  travel  the  charge  within  the 
cylinder  is  expanded,  whereupon  the  inlet  ports  are  un- 
covered and  remain  open  for  40  degrees  of  cylinder 
travel,  20  degrees  on  each  side  of  the  inward  dead  center 
position. 

SPRINGLESS    VALVES 

Springless  valves  are  the  latest  development  on  French 
racing  car  engines,  and  it  is  possible  that  the  positively- 
operated  types  will  be  introduced  on  aviation  engines 
also.  Two  makes  of  positively-actuated  valves  are  shown 
at  Fig.  6.  The  positive-valve  motor  differs  from  the  con- 
ventional form  by  having  no  necessity  for  valve-springs, 
as  a  cam  not  only  assures  the  opening  of  the  valve,  but 
also  causes  it  to  return  to  the  valve-seat.  In  this  respect 
it  is  much  like  the  sleeve-valve  motor,  where  the  uncover- 
ing of  the  ports  is  absolutely  positive.  The  cars  equipped 
with  these  valves  were  a  success  in  long-distance  auto 
races.  Claims  made  for  this  type  of  valve  mechanism 
include  the  possibility  of  a  higher  number  of  revolutions 
and  consequently  greater  engine  power.  With  the  spring- 
controlled,  single-cam  operated  valve  a  point  is  reached 
where  the  spring  is  not  capable  of  returning  the  valve 


Springless  Valves 


281 


to  its  seat  before  the  cam  has  again  begun  its  opening 
movement.  It  is  possible  to  extend  the  limits  consider- 
ably by  using  a  light  valve  on  a  strong  spring,  but  the 


Igriif't-on 


Fig.    111. — Timing   Diagram   Showing   Peculiar   Valve    Timing   of   Gnome 
"Monosoupape"  Rotary  Motor. 

valve  still  remains  a  limiting  factor  in  the  speed  of  the 
motor. 

A  part  sectional  view  through  a  cylinder  of  an  engine 
designed  by  G.  Michaux  is  shown  at  Fig.  112,  A.  There 
are  two  valves  per  cylinder,  inclined  at  about  ten  degrees 
from  the  vertical.  The  valve-stems  are  of  large  diameter, 
as  owing  to  positive  control,  there  is  no  necessity  of 
lightening  this  part  in  an  unusual  degree.  A  single  over- 


282 


Aviation  Engines 


head  cam-shaft  has  eight  pairs  of  cams,  which  are  shown 
in  detail  at  B.  For  each  valve  there  is  a  three-armed 
rocker,  one  arm  of  which  is  connected  to  the  stem  of  the 
valve  and  the  two  others  are  in  contact,  respectively  with 
the  opening  and  closing  cams.  The  connection  to  the 
end  of  the  valve-stem  is  made  by  a  short  connecting  link, 
which  is  screwed  on  to  the  tnd  of  the  valve-stem  and 


Yoke 
Guide 


Cam  Shaft 

Housing 

Supports 


Cam  Shaft  Housing 
Cam 
Valve  Operating  Yoke 


Fig.  112. — Two  Methods  of  .Operating  Valves  by  Positive  Cam  Mechanism 
Which  Closes  as  Well  as  Opens  Them. 

locked  in  position.  This  allows  some  adjustment  to'  be 
made  between  the  valves  and  the  actuating  rocker.  It  will 
be  evident,  that  one  cam  and  one  rocker  arm  produce 
the  opening  of  the  valve  and  that  the  corresponding 
rocker  arm  and  cam  result  in  the  closing  of  the  valve. 
If  the  opening  cam  has  the. usual  convex  profile,  the  clos- 
ing cam  has  a  correspondingly  concave  profile.  It  will 
be  noticed  that  a  light  valve- spring  is  shown  in  drawing. 
This  is  provided  to  give  a  final  seating  to  its  valve  after 


Positive  Valve  Systems  283 

it  lias  been  closed  by  the  cam.  This  is  not  absolutely 
necessary,  as  an  engine  has  been  run  successfully  with- 
out these  springs.  The  whole  mechanism  is  contained 
within  an  overhead  aluminum  cover. 

The  positive-valve  system  used  on  the  De  Lage  motor 
is  shown  at  D.  In  this  the  valves  are  actuated  as  shown 
in  sectional  views  D  and  E.  The  valve  system  is  unique 
in  that  four  valves  are  provided  per  cylinder,  two  for 
exhaust  and  two  for  intake.  The  valves  are  mounted 
side  by  side,  as  shown  at  E,  so  the  double  actuator  mem- 
ber may  be  operated  by  a  single  set  of  cams.  The  valve-- 
operating  member  consists  of  a  yoke  having  guide  bars 
at  the  top  and  bottom.  The  actuating  cam  works  inside 
of  this  yoke.  The  usual  form  of  cam  acts  on  the  lower 
portion  of  the  yoke  to  open  the  valve,  while  the  concave 
cam  acts  on  the  upper  part  to  close  the  valves.  In  this 
design  provision  is  made  for  expansion  of  the  valve-stems 
due  to  heat,  and  these  are  not  positively  connected  to  the 
actuating  member.  As  shown  at  E,  the  valves  are  held 
against  the  seat  by  short  coil  springs  at  the  upper  end 
of  the  stem.  These  are  very  stiff  and  are  only  intended 
to  provide  for  expansion.  A  slight  space  is  left  between 
the  top  of  the  valve-stem  and  the  portion  of  the  operat- 
ing member  that  bears  against  them  when  the  regular 
profile  cam  exerts  its  pressure  on  the  bottom  of  the  valve- 
operating  mechanism.  Another  novelty  in  this  motor 
design  is  that  the  cam-shafts  and  the  valve-operating 
members  are  carried  in  casing  attached  above  the  motor 
by  housing  supports  in  the  form  of  small  steel  pillars. 
The  overhead  cam-shafts  are  operated  by  means  of  bevel 
gearing. 

FOUR  VALVES  PER  CYLINDER   .:»  : 

Mention  has  been  previously  made  of  the  sixteen- 
valve  four-cylinder  Duesenberg  motor  and  its  great  power 
output  for  the  piston  displacement.  This  is  made  pos- 
sible by  the  superior  volumetric  efficiency  of  a  motor 
provided  with  four  valves  in  each  cylinder  instead  of 


284 


Aviation  Engines 


but  two.  This  principle  was  thoroughly  tried  out  in  rac- 
ing automobile  motors,  and  is  especially  valuable  in  per- 
mitting of  greater  speed  and  power  output  from  simple 
four-  and  six-cylinder  engines.  On  eight-  and  twelve- 
cylinder  types,  it  is  doubtful  if  the  resulting  complica- 
tion due  to  using  a  very  large  number  of  valves  would 
be  worth  while.  When  extremely  large  valves  are  used, 


---~~-'* Two  Small 
Valves 


'One  Large 
Valve 


Fig.  113. — Diagram  Comparing  Two  Large  Valves  and  Four  Small  Ones 
of  Practically  the  Same  Area.  Note  How  Easily  Small  Valves  are 
Installed  to  Open  Directly  Into  the  Cylinder. 

as  shown  in  diagram  at  Fig.  113,  it  is  difficult  to  have 
them  open  directly  into  the  cylinder,  and  pockets  are 
sometimes  necessary.  A  large  valve  would  weigh  more 
than  two  smaller  valves  having  an  area  slightly  larger 
in  the  aggregate;  it  would  require  a  stiff er  valve  spring 
on  account  of  its  greater  weight.  A  certain  amount  of 
metal  in  the  valve-head  is  necessary  to  prevent  warping; 
therefore,  the  inertia  forces  will  be  greater  in  the  large 
valve  than  in  the  two  smaller  valves.  As  a  greater  port 


Multiple  Valve  Advantages 


285 


286 


Aviation  Engines 


area  is  obtained  by  the  use  of  two  valves,  the  gases  will 
be  drawn  into  the  cylinder  or  expelled  faster  than  with 
a  lesser  area.  Even  if  the  areas  are  practically  the  same 
as  in  the  diagram  at  Fig.  113,  the  smaller  valves  may 


Inlet  Valve  Depressing  Lever 


Push  Rod 


Exhaust  Valve 
Actuating 
Lever. 


Cylinder  hold 


Propeller  Hub 


Oil  Gauge  — 


Oil  Pump- 


Fig.  115. — Front  View  of  Curtiss  OX3  Aviation  Motor,  Showing  Uncon- 
ventional Valve  Action  by  Concentric  Push  Rod  and  Pull  Tube. 

have  a  greater  lift  without  imposing  greater  stresses  on 
the  valve-operating  mechanism  and  quicker  gas  intake 
and  exhaust  obtained.  The  smaller  valves  are  not  af- 
fected by  heat  as  much  as  larger  ones  are.  The  quicker 
gas  movements  made  possible,  as  well  as  reduction  of 


Multiple  Valve  Advantages  287 

inertia  forces,  permits  of  higher  rotative  speed,  and, 
consequently,  greater  power  output  for  a  given  piston 
displacement.  The  drawings  at  Fig.  114  show  a  sixteen- 
valve  motor  of  the  four-cylinder  type  that  has  been  de- 
signed for  automobile  racing  purposes,  and  it  is  apparent 
that  very  slight  modifications  would  make  it  suitable  for 
aviation  purposes.  Part  of  the  efficiency  is  due  to  the 
reduction  of  bearing'  friction  by  the  use  of  ball  bearings, 
but  the  multiple-valve  feature  is  primarily  responsible 
for  the  excellent  performance. 


CHAPTER   IX 

Constructional  Details  of  Pistons — Aluminum  Cylinders  and  Pistons — 
Piston  Ring  Construction — Leak  Proof  Piston  Rings — Keeping 
Oil  Out  of  Combustion  Chamber — Connecting  Rod  Forms — Con- 
necting Rods  for  Vee  Engines — Cam-Shaft  and  Crank-Shaft  De- 
signs— Ball  Bearing  Crank-Shafts — Engine  Base  Construction. 

CONSTRUCTIONAL   DETAILS   OF   PISTONS 

The  piston  is  one  of  the  most  important  parts  of  the 
gasoline  motor  inasmuch  as  it  is  the  reciprocating  mem- 
ber that  receives  the  impact  of  the  explosion  and  which 
transforms  the  power  obtained  by  the  combustion  of  gas 
to  mechanical  motion  by  means  of  the  connecting  rod  to 
which  it  is  attached.  The  piston  is  one  of  the  simplest 
elements  of  the  motor,  and  it  is  one  component  which 
does  not  vary  much  in  form  in  different  types  of  motors. 
The  piston  is  a  cylindrical  member  provided  with  a  series 
of  grooves  in  which  packing  rings  are  placed  on  the  out- 
side and  two  bosses  which  serve  to  hold  the  wrist  pin  in 
its  interior.  It  is  usually  made  of  cast  iron  or  aluminum, 
though  in  some  motors  where  extreme  lightness  is  de- 
sired, such  as  those  used  for  aeronautic  work,  it  may  be 
made  of  steel.  The  use  of  the  more  resisting  material 
enables  the  engineer  to  use  lighter  sections  where  it  is 
important  that  the  weight  of  this  member  be  kept  as  low 
as  possible  consistent  with  strength. 

A  number  of  piston  types  are  shown  at  Fig.  116.  That 
at  A  has  a  round  top  and  is  provided  with  four  split 
packing  rings  and.  two  oil  grooves.  A  piston  of  this  type 
is  generally  employed  in  motors  where  the  combustion 
chamber  is  large  and  where  it  is  desired  to  obtain  a 
higher  degree  of  compression  than  would  be  possible  with 
a  flat  top  piston.  This  construction  is  also  stronger  be- 
cause of  the  arched  piston  top.  The  most  common  form 


Constructional  Details  of  Pistons 


289 


of  piston  is  that  shown  at  B,  and  it  differs  from  that 
previously  described  only  in  that  it  has  a  flat  top.  The 
piston  outlined  in  section  at  C  is  a  type  used  on  some 
of  the  sleeve-valve  motors  of  the  Knight  pattern,  and 
has  a  concave  head  instead  of  the  convex  form  shown 
at  A.  The  design  shown  at  D  in  side  and  plan  views  is 


Side  View 


Fig.  116. — Forms  of  Pistons  Commonly  Employed  in  Gasoline  Engines. 
A — Dome  Head  Piston  and  Three  Packing  Kings.  B — Flat  Top  Form 
Almost  Universally  Used.  C — Concave  Piston  Utilized  in  Knight 
Motors  and  Some  Having  Overhead  Valves.  D — Two-Cycle  Engine 
Member  with  Deflector  Plate  Cast  Integrally.  E — Differential  of 
Two-Diameter  Piston  Used  in  Some  Engines  Operating  on  Two-Cycle 
Principle. 

the  conventional  form  employed  in  two-cycle  engines. 
The  deflector  plate  on  the  top  of  the  cylinder  is  cast  in- 
tegral and  is  utilized  to  prevent  the  incoming  fresh  gases 
from  flowing  directly  over  the  piston  top  and  out  of  the 
exhaust  port,  which  is  usually  opposite  the  inlet  open- 
ing. On  these  types  of  two-cycle  engines  where  a  two- 
diameter  cylinder  is  employed,  the  piston  shown  at  E  is 


290 


Aviation  Engines 


i 


fio  I  § 

fl      FHO 


- 

45* 


tl 


l 


lifts 


. 
I  -8  B  5  « 

«   O    rt    53   5 


p4  fe   ai  P-i   3 

5!  If  I 

60 


Constructional  Details  of  Pistons 


291 


used.  This  is  known  as  a  "differential  piston,"  and  has 
an  enlarged  portion  at  its  lower  end  which  fits  the  pump- 
ing cylinder.  The  usual  form  of  deflector  plate  is  pro- 


Piston  Rings 


Piston  Ring 
Grooves 


Wrist  Pin 


Piston 


Connecting  Rod- 


Connecting  Rod  Bearing 

Bearing  Liner's 
Connecting  Rod  Cap 

Connecting  Rod  Bolts 


Oil  Scoop 


Fig.  118. — Typical  Piston  and  Connecting  Rod  Assembly. 

vided  at  the  top  of  the  piston  and  one  may  consider  it 
as  two  pistons  in  one. 

One  of  the  important  conditions  in  piston  design  is 
the  method  of  securing  the  wrist  pin  which  is  used  to 


292 


Aviation  Engines 


connect  the  piston  to  the  upper  end  of  the  connecting 
rod.  Various  methods  have  been  devised  to  keep  the 
pin  in  place,  the  most  common  of  these  being  shown  at 
Fig.  117.  The  wrist  pin  should  be  retained  by  some 
positive  means  which  is  not  liable  to  become  loose  under 
the  vibratory  stresses  which  obtain  at  this  point.  If  the 


Spark  Plugs 


Spark 


Connecting  Rod 
Big  End  Boxes 


Pis -ran 
Rings- 


'-•Connecting   Rod  M/  •   ,  n      D      ,         • 

Wrist  Pin  Bushing- 

•  Ring  Grooves 


Piston 


Fig.    119. — Parts    of    Sturtevant    Aviation    Engine.      A — Cylinder    Head 
Showing  Valves.     B — Connecting  Rod.     C — Piston  and  Rings. 


Constructional  Details  of  Pistons  293 

wrist  pin  was  free  to  move  it  would  work  out  of  the 
bosses  enough  so  that  the  end  would  bear  against  the 
cylinder  wall.  As  it  is  usually  made  of  steel,  which  is  a 
harder  material  than  cast  iron  used  in  cylinder  construc- 
tion, the  rubbing  action  would  tend  to  cut  a  groove  in 
the  cylinder  wall  which  would  make  for  loss  of  power 


Fig.  120. — Aluminum  Piston  and  Light  But  Strong  Steel  Connecting  Rod 
and  Wrist  Pin  of  Thomas  Aviation  Engine. 

because  it  would  permit  escape  of  gas.  The  wrist  pin 
member  is  a  simple  cylindrical  element  that  fits  the  bosses 
closely,  and  it  may  be  either  hollow  or  solid  stock.  A 
typical  piston  and  connecting  rod  assembly  which  shows 
a  piston  in  section  also  is  given  at  Fig.  118.  The  piston 
of  the  Sturtevant  aeronautical  motor  is  shown  at  Fig. 
119,  the  aluminum  piston  of  the  Thomas  airplane  motor 
with  piston  rings  in  place  is  shown  at  Fig.  120.  A  good 
view  of  the  wrist  pin  and  connecting  rod  are  also  given. 
The  iron  piston  of  the  Gnome  "Monosoupape"  airplane 
engine  and  the  unconventional  connecting  rod  assembly 
are  clearly  depicted  at  Fig  121. 

The  method  of  retention  shown  at  A  is  the  simplest 
and  consists  of  a  set  screw  having  a  projecting  portion 


294  Aviation  Engines 

passing  into  the  wrist  pin  and  holding  it  in  place.  The 
screw  is  kept  from  turning  or  loosening  by  means  of  a 
check  nut.  The  method  outlined  at  B  is  similar  to  that 
shown  at  A,  except  that  the  wrist  pin  is  solid  and  the 
point  of  the  set  screw  engages  an  annular  groove  turned 
in  the  pin  for  its  reception.  A  very  positive  method- is 
shown  at  C.  Here  the  retention  screws  pass  into  the 
wrist  pin  and  are  then  locked  by  a  piece  of  steel  wire 
which  passes  through  suitable  holes  in  the  ends.  The 
method  outlined  at  D  is  sometimes  employed,  and  it  varies 


Fig.  121. — Cast  Iron  Piston  of   "Monosoupape"   Gnome  Engine  Installed 
On  One  of  the  Short  Connecting  Eods. 

from  that  shown  at  C  only  in  that  the  locking  wire,  which 
is  made  of  spring  steel,  is  passed  through  the  heads  of 
the  locking  screws.  Some  designers  machine  a  large 
groove  around  the  piston  at  such  a  point  that  when  the 
wrist  pin  is  put  in  place  a  large  packing  ring  may  be 
sprung  in  the  groove  and  utilized  to  hold  the  wrist  pin 
in  place. 

The  system  shown  at  F  is  not  so  widely  used  as  the 
simpler  methods,  because  it  is  more  costly  and  does  not 
offer  any  greater  security  when  the  parts  are  new  than 
the  simple  lock  shown  at  A.  In  this  a  hollow  wrist  pin  is 
used,  having  a  tapered  thread  cut  at  each  end.  The  wrist 
pin  is  slotted  at  three  or  four  points,  for  a  distance  equal 
to  the  length  of  the  boss,  and  when  taper  expansion  plugs 


Piston  Pin  Retention  295 

are  screwed  in  place  the  ends  of  the  wrist  pin  are  ex- 
panded against  the  bosses.  This  method  has  the  advan- 
tage of  providing  a  certain  degree  of  adjustment  if  the 
wrist  pin  should  loosen  up  after  it  has  been  in  use  for 
some  time.  The  taper  plugs  would  be  screwed  in  deeper 
and  the  ends  of  the  wrist  pin  expanded  proportionately 
to  take  up  the  loss  motion.  The  method  shown  at  Gf  is 
an  ingenious  one.  One  of  the  piston  bosses  is  provided 
with  a  projection  which  is  drilled  out  to  receive  a  plunger. 
The  wrist  pin  is  provided  with  a  hole  of  sufficient  size  to 
receive  the  plunger,  which  is  kept  in  place  by  means  of 
a  spring  in  back  of  it.  This  makes  a  very  positive  lock 
and  one  that  can  be  easily  loosened  when  it  is  desired  to 
remove  the  wrist  pin.  To  unlock,  a  piece  of  fine  rod  is 
thrust  into  the  hole  at  the  bottom  of  the  boss  which  pushes 
the  plunger  back  against  the  spring  until  the  wrist  pin 
can  be  pushed  out  of  the  piston. 

Some  engineers  think  it  advisable  to  oscillate  the  wrist 
pin  in  the  piston  bosses,  instead  of  in  the  connecting  rod 
small  end.  It  is  argued  that  this  construction  gives  more 
bearing  surface  at  the  wrist  pin  and  also  provides  for 
more  strength  because  of  the  longer  bosses  that  can  be 
used.  When  this  system  is  followed  the  piston  pin  is 
held  in  place  by  locking  it  to  the  connecting  rod  by  some 
means.  At  H  the  simplest  method  is  outlined.  This  con- 
sisted of  driving  a  taper  pin  through  both  rod  and  wrist 
pin  and  then  preventing  it  from  backing  out  by  putting 
a  split  cotter  through  the  small  end  of  the  tapered,  lock- 
ing pin.  Another  method,  which  is  depicted  at  I,  consists 
of  clamping  the  wrist  pin  by  means  of  a  suitable  bolt 
which  brings  the  slit  connecting  rod  end  together  as 
shown. 

ALUMINUM    FOR   CYLINDERS   AND   PISTONS 

Aluminum  pistons  outlined  at  Fig.  122,  have  replaced 
cast  iron  members  in  many  airplane  engines,  as  these 
weigh  about  one-third  as  much  as  the  cast  iron  forms  of 
the  same  size,  while  the  reduction  in  the  inertia  forces 


296 


Aviation  Engines 


has  made  it  possible  to  increase  the  engine  speed  without 
correspondingly  stressing  the  connecting  rods,  crank-shaft 
and  engine  bearings. 

Aluminum  has  not  only  been  used  for  pistons,  but  a 
number  of  motors  will  be  built  for  the  coming  season  that 
will  use  aluminum  cylinder  block  castings  as  well.  Of 
course,  the  aluminum  alloy  is  too  soft  to.be  used  as  a 
bearing  for  the  piston,  and  it  will  not  withstand  the  ham- 
mering action  of  the  valve.  This  makes  the  use  of  cast 


(-""Ribs 


,'Hourglass 
\       Piston 


Racing 
Piston 


''Recesses  in  Casting 
Hourglass  Piston*. 


,Ribs  for  Strength  and 
•      Heat  Radiation* 


Wrist  Pin  Boss'"' 


Sections  of  Aluminum  Piston 


Fig.  122. — Types  of  Aluminum  Pistons  Used  In  Aviation  Engines, 

iron  or  steel  imperative  in  all  motors.  When  used  in  con- 
nection with  an  aluminum  cylinder  block  the  cast  iron 
pieces  are  placed  in  the  mould  so  that  they  act  as  cylinder 
liners  and  valve  seats,  and  the  molten  metal  is  poured 
around  them  when  the  cylinder  is  cast.  It  is  said  that 
this  construction  results  in  an  intimate  bond  between  the 
cast  iron  and  the  surrounding  aluminum  metal.  Steel 
liners  may  also  be  pressed  into  the  aluminum  cylinders 
after  these  are  bored  out  to  receive  them.  Aluminum 
has  for  a  number  of  years  been  used  in  many  motor 


Aluminum  Pistons  297 

car  parts.  Alloys  have  been  developed  that  have  greater 
strength  than  cast  iron  and  that  are  not  so  brittle.  Its 
use  for  manifolds  and  engine  crank  and  gear  cases  has 
been  general  for  a  number  of  years. 

At  first  thought  it  would  seem  as  though  aluminum 
would  be  entirely  unsuited  for  use  in  those  portions  of 
internal  combustion  engines  exposed  to  the  heat  of  the 
explosion,  on  account  of  the  low  melting  point  of  that 
metal  and  its  disadvantageous  quality  of  suddenly  "  wilt- 
ing "  when  a  critical  point  in  the  temperature  is  reached. 
Those  who  hesitated  to  use  aluminum  on  account  of  this 
defect  lost  sight  of  the  great  heat  conductivity  of  that 
metal,  which  is  considerably  more  than  that  of  cast  iron. 
It  was  found  in  early  experiments  with  aluminum  pistons 
that  this  quality  of  quick  radiation  meant  that  aluminum 
pistons  remained  considerably  cooler  than  cast  iron  ones 
in  service,  which  was  attested  to  by  the  reduced  forma- 
tion of  carbon  deposits  thereon.  The  use  of  aluminum 
makes  possible  a  marked  reduction  in  power  plant  weight. 
A  small  four-cylinder  engine  which  was  not  particularly 
heavy  even  with  cast  iron  cylinders  was  found  to  weigh 
100  pounds  less  when  the  cylinder  block,  pistons,  and 
upper  half  of  the  crank-case  had  been  made  of  aluminum 
instead  of  cast  iron.  Aluminum  motors  are  no  longer 
an  experiment,  as  a  considerable  number  of  these  have 
been  in  use  on  cars  during  the  past  year  without  the 
owners  of  the  cars  being  apprised  of  the  fact.  Absolutely 
no  complaint  was  made  in  any  case  of  the  aluminum 
motor  and  it  was  demonstrated,  in  addition  to  the  saving 
in  weight,  that  the  motors  cost  no  more  to  assemble  and 
cooled  much  more  efficiently  than  the  cast  iron  form.  One 
of  the  drawbacks  to  the  use  of  aluminum  is  its  growing 
scarcity,  which  results  in  making  it  a  "near  precious" 
metal. 

PISTON   RING   CONSTRUCTION 

As  all  pistons  must  be  free  to  move  up  and  down  in 
the  cylinder  with  minimum  friction,  they  must  be  less  in 


298  Aviation  Engines 

diameter  than  the  bore  of  the  cylinder.  The  amount  of 
freedom  or  clearance  provided  varies  with  the  construc- 
tion of  the  engine  and  the  material  the  piston  is  made  of, 
as  well  as  its  size,  but  it  is  usual  to  provide  from  .005  to 
.010  of  an  inch  to  compensate  for  the  expansion  of  the 
piston  due  to  heat  and  also  to  leave  sufficient  clearance 
for  the  introduction  of  lubricant  between  the  working 
surfaces.  "Obviously,  if  the  piston  were  not  provided  with 
packing  rings,  this  amount  of  clearance  would  enable  a 
portion  of  the  gases  evolved  when  the  charge  is  exploded 
to  escape  by  it  into  the  engine  crank-case.  The  packing 


D 


Fig.  123. — Types  of  Piston  Rings  and  Ring  Joints.  A — Concentric  Ring. 
B— Eccentrically  Machined  Form.  C — Lap  Joint  Ring.  D — Butt  Joint, 
Seldom  Used.  E — Diagonal  Cut  Member,  a  Popular  Form. 


members  or  piston  rings,  as  they  are  called,  are  split 
rings  of  cast  iron,  which  are  sprung  into  suitable  grooves 
machined  on  the  exterior  of  the  piston,  three  or  four  of 
these  being  the  usual  number  supplied.  These  have  suffi- 
cient elasticity  so  that  they  bear  tightly  against  the  cylin- 
der wall  and  thus  make  a  gas-tight  joint.  Owing  to  the 
limited  amount  of  surface  in  contact  with  the  cylinder 
wall  and  the  elasticity  of  the  split  rings  the  amount  of 
friction  resulting  from  the  contact  of  properly  fitted  rings 
and.  the  cylinder  is  not  of  enough  moment  to  cause  any 
damage  and  the  piston  is  free  to  slide  up  and  down  in 
the  cylinder  bore. 

These  rings  are  made  in  two  forms,  as  outlined  at 
Fig.  123.    The  design  shown  at  A  is  termed  a  "  concentric 


Piston  Ring  Forms  299 

ring,"  because  the  inner  circle  is  concentric  with  the 
outer  one  and  the  ring"  is  of  uniform  thickness  at  all 
points.  The  ring  shown  at  B  is  called  an  "eccentric 
ring,"  and  it  is  thicker  at  one  part  than  at  others.  It 
has  theoretical  advantages  in  that  it  will  make  a  tighter 
joint  than  the  other  form,  as  it  is  claimed  its  expansion 
due  to  heat  is  more  uniform.  The  piston  rings  must  be 
split  in  order  that  they  may  be  sprung  in  place  in  the 
grooves,  and  also  to  insure  that  they  will  have  sufficient 
elasticity  to  take  the  form  of  the  cylinder  at  the  different 
points  in  their  travel.  If  the  cylinder  bore  varies  by 
small  amounts  the  rings  will  spring  out  at  the  points 
where  the  bore  is  larger  than  standard,  and  spring  in  at 
those  portions  where  it  is  smaller  than  standard. 

It  is  important  that  the  joint  should  be  as  nearly  gas- 
tight  as  possible,  because  if  it  were  not  a  portion  of  the 
gases  would  escape  through  the  slots  in  the  .piston  rings. 
The  joint  shown  at  C  is  termed  a  "lap  joint,"  because 
the  ends  of  the  ring  are  cut  in  such  a  manner  that  they 
overlap.  This  is  the  approved  joint.  The  butt  joint 
shown  at  D  is  seldom  used  and  is  a  very  poor  form,  the 
only  advantage  being  its  cheapness.  The  diagonal  cut 
shown  at  E  is  a  compromise  between  the  very  good  form 
shown  at  C  and  the  poor  joint  depicted  at  D.  It  is  also 
widely  used,  though  most  constructors  prefer  the  lap 
joint,  because  it  does  not  permit  the  leakage  of  gas  as 
much  as  the  other  two  types. 

There  seems  to  be  some  difference  of  opinion  relative 
to  the  best  piston  ring  type — some  favoring  the  eccentric 
pattern,  others  the  concentric  form.  The  concentric  ring 
has  advantages  from  the  lubricating  engineer's  point  of 
view;  as  stated  by  the  Platt  &  Washburn  Company  in 
their  text-book  on  engine  lubrication,  the  smaller  clear- 
ance behind  the  ring  possible  with  the  ring  of  uniform 
section  is  advantageous. 

Fig.  124,  A,  shows  a  concentric  piston  ring  in  its 
groove.  Since  the  ring  itself  is  concentric  with  the 
groove,  very  small  clearance  between  the  back  of  the  ring 


300 


Aviation  Engines 


and  the  bottom  of  its  groove  may  be  allowed.  Small 
clearance  leaves  less  space  for  '  the  accumulation  of  oil 
and  carbon  deposits.  The  gasket  effect  of  this  ring  is 
uniform  throughout  the  entire  length  of  its  edges,  which 
is  its  marked  advantage  over  the  eccentric  ring.  This 
type  of  piston  ring  rarely  burns  fast  in  its  groove.  There 
are  a  large  number  of  different  concentric  rings  manu- 
factured of  different  designs  and  of  different  efficiency. 
Figs.  124,  B  and  124,  C  show  eccentric  rings  assembled 
in  the  ring  groove.  It  will  be  noted  that  there  is  a  large 


Cylinder^      .Clearance 


learance         CyJmder\ 


Clearance. 


Wafer.-' 
Jacket 


Eccentric  Ring- 

C 


Fig-.  124. — Diagrams  Showing  Advantages  of  Concentric  Piston  Rings. 

space  between  the  thin  ends  of  this  ring  and  the  bottom 
of  the  groove.  This  empty  space  fills  up  with  oil  which 
in  the  case  of  the  upper  ring  frequently  is  carbonized, 
restricting  the  action  of  the  ring  and  nullifying  its  use- 
fulness. The  edges  of  the  thin  ends  are  not  sufficiently 
wide  to  prevent  rapid  escape  of  gases  past  them.  In  a 
practical  way  this  leakage  means  loss  of  compression  and 
noticeable  drop  in  power.  When  new  and  properly  fitted, 
very  little  difference  can  be  noted  between  the  tightness 
of  eccentric  and  concentric  rings.  Nevertheless,  after 
several  months'  use,  a  more  rapid  leakage  will  always 
occur  past  the  eccentric  than  past  the  concentric.  If 
continuous  trouble  with  the  carbonization  of  cylinders, 
smoking  and  sooting  of  spark-plugs  is  experienced,  it  is 


Leak-Proof  Piston  Rings  301 

a  sure  indication  that  mechanical  defects  exist  in  the  en- 
gine, assuming  of  course,  that  a  suitable  oil  has  been 
used.  Such  trouble  can  be  greatly  lessened,  if  not  en- 
tirely eliminated,  by  the  application  of  concentric  rings 
(lap  joint),  of  any  good  make,  properly  fitted  into  the 
grooves  of  the  piston.  Too  much  emphasis  canno^  be 
put  upon  this  point.  If  the  oil  used  in  the  engine  is  of 
the  correct  viscosity,  and  serious  carbon  deposit,  smoking, 
etc.,  still  result,  the  only  certain  remedy  then  is  to  have 
the  cylinders  rebored  and  fitted  with  properly  designed, 
oversized  pistons  and  piston  rings. 


LEAK-PROOF   PISTON  RINGS 

In  order  to  reduce  the  compression  loss  and  leakage 
of  gas  by  the  ordinary  simple  form  of  diagonal  or  lap 
joint  one-piece  piston  ring  a  number  of  compound  rings 
have  been  devised  and  are  offered  by  their  makers  to 
use  in  making  replacements.  The  leading  forms  are 
shown  at  Fig.  125.  That  shown  at  A  is  .  known  as  the 
"Statite"  and  consists  of  three  rings,  one  carried  inside 
while  the  other  two  are  carried  on  the  outside.  The  ring 
shown  at  B  is  a  double  ring  and  is  known  as  the  McCad- 
den.  This  is  composed  of  two  thin  concentric  lap  joint 
rings  so  disposed  relative  to  each  other  that  the  opening 
in  the  inner  ring  comes  opposite  to  the  opening  in  the 
outer  ring. 

The  form  shown  at  C  is  known  as  the  "Leektite," 
and  is  a  single  ring  provided  with  a  peculiar  form  of  lap 
and  dove  tail  joint.  The  ring  shown  at  D  is  known  as 
the  "Dunham"  and  is  of  the  double  concentric  type  being 
composed  of  two  rings  with  lap  joints  which  are  welded 
together  at  a  point  opposite  the  joint  so  that  there  is  no 
passage  by  which  the  gas  can  escape.  The  Burd  high 
compression  ring  is  shown  at  E.  The  joints  of  these 
rings  are  sealed  by  means  of  an  H-shaped  coupler  of 
bronze  which  closes  the  opening.  The  ring  ends  are  made 
with  tongues  which  interlock  with  the  coupling.  The 


302 


Aviation  Engines 


ring  shown  at  F  is  called  the  "Evertite"  and  is  a  three- 
piece  ring  composed  of  three  members  as  shown  in  the 
sectional  view  below  the  ring.  The  main  part  or  inner 
ring  has  a  circumferential  channel  in  which  the  two  outer 
rings  lock,  the  resulting  cross-section  being  rectangular 
just  the  same  as  that  of  a  regular  pattern  ring.  All 
three  rings  are  diagonally  split  and  the  joints  are  spaced 
equally  and  the  distances  maintained  by  small  pins.  This 


SECTION  OF  RING    F 


Fig.  125. — Leak-Proof  and  Other  Compound  Piston  Rings. 

results  in  each  joint  being  sealed  by  the  solid  portion  of 
the  other  rings. 

The  use  of  a  number  of  light  steel  rings  instead  of 
one  wide  ring  in  the  groove  is  found  on  a  number  of 
automobile  power  plants,  but  as  far  as  knowTi,  this  con- 
struction is  not  used  in  airplane  power  plants.  It  is 
contended  that  where  a  number  of  light  rings  is  em- 
ployed a  more  flexible  packing  means  is  obtained  and  the 
possibility  of  leakage  is  reduced.  Eings  of  this  design 
are  made  of  square  section  steel  wire  and  are  given  a 
spring  temper.  Owing  to  the  limited  width  the  diagonal 


Keeping  Oil  Out  of  Combustion  Chambers      303 

cut  joint  is  generally  employed  instead  of  the  lap  joint 
which  is  so  popular  on  wider  rings* 


KEEPING   OIL   OUT   OF    COMBUSTION    CHAMBERS 

An  examination  of  the  engine  design  that  is  econom- 
ical in  oil  consumption  discloses  the  use  of  tight  piston 
rings,  large  centrifugal  rings  on  the  crank-shaft  where  it 
passes  through  the  case,  ample  cooling  fins  in  the  pistons, 
vents  between  the  crank-case  chamber  and  the  valve  en- 
closures, etc.  Briefly  put,  cooling  of  the  oil  in  this  engine 
has  been  properly  cared  for  and  leakage  reduced  to  a 
minimum.  To  be  specific  regarding  details  of  design: 
Oil  surplus  can  be  kept  out  of  the  explosion  chambers  by 
leaving  the  lower  edge  of  the  piston  skirt  sharp  and  by 
the  use  of  a  shallow  groove  (C),  Fig.  126,  just  below  the 
lower  piston  ring.  Small  holes  are  bored  through  the 
piston  walls  at  the  base  of  this  groove  and  communicate 
with  the  crank-case.  The  similarity  of  the  sharp  edges 
of  piston  skirt  (D)  and  piston  ring  to  a  carpenter's  plane 
bit,  makes  their  operation  plain. 

The  cooling  of  oil  in  the  sump  (A)  can  be  accom- 
plished most  effectively  by  radiating  fins  on  its  outer 
surface.  The  lower  crank-case  should  be  fully  exposed  to 
the  outer  air.  A  settling  basin  for  sediment  (B)  should 
be  provided  having  a  cubic  content  not  less  than  one- 
tenth  of  the  total  oil  capacity  as  outlined  at  Fig.  126. 
The  depth  of  this  basin  should  be  at  least  2%  inches,  and 
its  walls  vertical,  as  shown,  to  reduce  the  mixing  of  sedi- 
ment with  the  oil  in  circulation.  The  inlet  opening  to 
the  oil  pump  should  be  near  the  top  of  the  sediment  basin 
in  order  to  prevent  the  entrance  into  the  pump  with  the 
oil  of  any  solid  matter  or  water  condensed  from  the  prod- 
ucts of  combustion.  This  sediment  basin  should  be 
drained  after  every  five  to  seven  hours  air  service  of  an 
airplane  engine.  Concerning  filtering  screens  there  is 
little  to  be  said,  save  that  their  areas  should  be  ample 
and  the  mesh  coarse  enough  (one- sixteenth  of  an  inch)  to 


304 


Aviation  Engines 


offer  no  serious  resistance  to  the  free  flow  of  cold  or 
heavy  oil  through  them;  otherwise  the  oil  in  the  crank- 
case  may  build  up  above  them  to  an  undesirable  level. 
The  necessary  frequency  of  draining  and  flushing  out  the 
oil  sump  differs  greatly  with  the  age  (condition)  of  the 


s-- 


Sump 


Sediment  Basin 


Fig.   126. — Sectional  View  of  Engine   Showing   Means   of   Preventing 
Oil   Leakage   By  Piston  Rings. 

engine  and  the  suitability  of  the  oil  used.  In  broad  terms, 
the  oil  sump  of  a  new  engine  should  be  thoroughly  drained 
and  flushed  with  kerosene  at  the  end  of  the  first  200 


Connecting  Rod  Forms  305 

miles,  next  at  the  end  of  500  miles  and  thereafter  every 
1,000  miles.  While  these  instructions  apply  specifically 
to  automobile  motors,  it  is  very  good  practice  to  change 
the  oil  in  airplane  engines  frequently.  In  many  cases, 
the  best  results  have  been  secured  when  the  oil  supply 
is  completely  replenished  every  five  hours  that  the  en- 
gine is  in  operation. 


CONNECTING   ROD   FORMS 

The  connecting  rod  is  the  simple  member  that  joins 
the  piston  to  the  crank-shaft  and  which  transmits  the 
power  imparted  to  the  piston  by  the  explosion  so  that  it 
may  be  usefully  applied.  It  transforms  the  reciprocating 
movement  of  the  piston  to  a  rotary  motion  at  the  crank- 
shaft. A  typical  connecting  rod  and  its  wrist  pin  are 
shown  at  Fig.  120.  It  will  be  seen  that  it  has  two  bear- 
ings, one  at  either  end.  The  small  end  is  bored  out  to 
receive  the  wrist  pin  which  joins  it  to  the  piston,  while 
the  large  end  has  a  hole  of  sufficient  size  to  go  on  the 
crank-pin.  The  airplane  and  automobile  engine  connect- 
ing rod  is  invariably  a  steel  forging,  though  in  marine 
engines  it  is  sometimes  made  a  steel  or  high  tensile 
strength  bronze  casting.  In  all  cases  it  is  desirable  to 
have  softer  metals  than  the  crank- shaft  and  wrist  pin  at 
the  bearing  point,  and  for  this  reason  the  connecting  rod 
is  usually  provided  with  bushings  of  anti-friction  or  white 
metal  at  the  lower  end,  and  bronze  at  the  upper.  The 
upper  end  of  the  connecting  rod  may  be  one  piece,  be- 
cause the  wrist  pin  can  be  introduced  after  it  is  in  place 
between  the  bosses  of  the  piston.  The  lower  bearing 
must  be  made  in  two  parts  in  most  cases,  because  the 
crank- shaft  cannot  be  passed  through  the  bearing  owing 
to  its  irregular  form.  The  rods  of  the  Gnome  engine  are 
all  one  piece  types,  as  shown  at  Fig.  127,  owing  to  the 
construction  of  the  "  mother "  rod  which  receives  the 
crank-pins.  The  complete  connecting  rod  assembly  is 
shown  in  Fig.  121,  also  at  A,  Fig.  127.  The  "  mother " 


306 


Aviation  Engines 


rod,  with  one  of  the  other  rods  in  place  and  one  about 
to  be  inserted,  is  shown  at  Fig.  127,  B.  The  built-up 
crank-shaft  which  makes  this  construction  feasible  is 
shown  at  Fig.  127,  B, 

Some  of  the  various  designs  of  connecting  rods  that 
have  been  used  are  shown  at  Fig.  128.  That  at  A  is  a 
simple  form  often  employed  in  single-cylinder  motors, 
having  built-up  crank-shafts.  Both  ends  of  the  connect- 


Fig.     127. — Connecting    Rod    and    Crank-Shaft    Construction    of    Gnome 
"Monosoupape"  Engine. 

ing  rod  are  bushed  with  a  one-piece  bearing,  as  it  can 
be  assembled  in  place  before  the  crank-shaft  assembly  is 
built  up.  A  built-up  crank-shaft  such  as  this  type  of  con- 
necting rod  would  be  used  with  is  shown  at  Fig.  106.  The 
pattern  shown  at  B  is  one  that  has  been  used  to  some 
extent  on  heavy  work,  and  is  known  as  the  "marine 
type."  It  is  made  in  three  pieces,  the  main  portion  being 
a  steel  forging  having  a- flanged  lower  end  to  which  the 
bronze  boxes  are  secured  by  bolts.  The  modified  marine 
type  depicted  at  C  is  the  form  that  has  received  the  wid- 
est application  in  automobile  and  aviation  engine  con- 


Connecting  Rod  Forms 


307 


308  Aviation  Engines 

struction.  It  consists  of  two  pieces,  the  main  member 
being  a  steel  drop  forging  having  the  wrist-pin  bearing 
and  the  upper  crank-pin  bearing  formed  integral,  while 
the  lower  crank-pin  bearing  member  is  a  separate  forg- 
ing secured  to  the  connecting  rod  by  bolts.  In  this  con- 
struction bushings  of  anti-friction  metal  are  used  at  the 
lower  end,  and  a  bronze  bushing  is  forced  into  the  upper- 
or  wrist-pin  end.  The  rod  shown  at  D  has  also  been 
widely  used.  It  is  similar  in  construction  to  the  form 
shown  at  C,  except  that  the  upper  end  is  split  in  order 
to  permit  of  a  degree  of  adjustment  of  the  wrist-pin 
bushing,  and  the  lower  bearing  cap  is  a  hinged  member 
which  is  retained  by  one  bolt  instead  of  two.  When  it  is 
desired  to  assemble  it  on  the  crank-shaft  the  lower  cap 
is  swung  to  one  side  and  brought  back  into  place  when 
the  connecting  rod  has  been  properly  located.  Sometimes 
the  lower  bearing  member  is  split  diagonally  instead  of 
horizontally,  such  a  construction  being  outlined  at  E. 

In  a  number  of  instances,  instead  of  plain  bushed 
bearings  anti-friction  forms  using  ball  or  rollers  have 
been  used  at  the  lower  end.  A  ball-bearing  connecting 
rod  is  shown  at  F.  The  big  end  may  be  made  in  one 
piece,  because  if  it  is  possible  to  get  the  ball  bearing  on 
the  crank-pins  it  will  be  easy  to  put  the  connecting  rod 
in  place.  Ball  bearings  are  not  used  very  often  on  con- 
necting rod  big.  ends  because  of  difficulty  of  installation, 
though  when  applied  properly  they  give  satisfactory  serv- 
ice and  reduce  friction  to  a  minimum.  One  of  the  ad- 
vantages of  the  ball  bearing  is  that  it  requires  no  adjust- 
ment, whereas  the  plain  bushings  depicted  in  the  other 
connecting  rods  must  be  taken  up  from  time  to  time  to 
compensate  for  wear. 

This  can  be  done  in  forms  shown  at  B?  C,  D,  and  E 
by  bringing  the  lower  bearing  caps  closer  to  the  upper 
one  and  scraping  out  the  brasses  to  fit  the  shaft.  A 
number  of  liners  or  shims  of  thin  brass  or  copper  stock, 
varying  from  .002  inch  to  .005  inch,  are  sometimes  inter- 
posed between  the  halves  of  the  bearings  when  it  is  first 


Connecting  Rod  Types  309 

fitted  to  the  crank-pin.  As  the  brasses  wear  the  shims 
may  be  removed  and  the  portions  of  the  bearings  brought 
close  enough  together  to  take  up  any  lost  motion  that 
may  exist,  though  in  some  motors  no  shims  are  provided 
and  depreciation  can  be  remedied  only  by  installing  new 
brasses  and  scraping  to  fit. 

The  various  structural  shapes  in  which  connecting  rods 
are  formed  are  shown  in  section  at  Gr.     Of  these  the  I 


~Ring  Grooves 


Connecting  Rod 
(Forked) 


Connecting  Rod  Bearing 
Cap 


Fig.   129. — Double  Connecting  Bod  Assembly  For  Use   On  Single  Crank- 
Pin  of  Vee  Engine. 

section  is  most  widely  used  in  airplane  engines,  because 
it  is  strong  and  a  very  easy  «hape  to  form  by  the  drop- 
forging  process  or  to  machine  out  of  the  solid  bar  when 
extra  good  steel  is  used.  Where  extreme  lightness  is 
desired,  as  in  small  high-speed  motors  used  for  cycle  pro- 
pulsion, the  section  shown  at  the  extreme  left  is  often 
used.  If  the  rod  is  a  cast  member  as  in  some  marine  en- 
gines, the  cross,  hollow  cylinder,  or  U  sections  are  some- 
times used.  If  the  sections  shown  at  the  right  are  em- 


310 


Aviation  Engines 


ployed,  advantage  is  often  taken  of  the  opportunity  for 
passing  lubricant  through  the  center  of  the  hollow  round 
section  on  vertical  motors  or  at  the  bottom  of  the  U 
section,  which  would  be  used  on  a  horizontal  cylinder 
power  plant. 

Connecting  rods  of  Vee  engines  are  made  in  two  dis- 
tinct styles.    The  forked  or  "scissors"  joint  rod  assembly 


Fig.  130. — Another  Type  of  Double  Connecting  Bod  for  Vee  Engines. 

is  employed  when  the  cylinders  are  placed  directly  op- 
posite each  other.  The  "blade"  rod,  as  shown  at  Fig. 
129,  fits  between  the  lower  ends  of  the  forked  rod,  which 
oscillate  on  the  bearing  which  encircles  the  crank-pin. 
The  lower  end  of  the  "blade"  rod  is  usually  attached  to 
the  bearing  brasses,  the  ends  of  the  "forked"  rod  move 
on  the  outer  surfaces  of  the  brasses.  Another  form  of 
rod  devised  for  use  under  these  conditions  is  shown  at 
Fig.  130  and  installed  in  an  aviation  engine  at  Fig.  132. 
In  this  construction  the  shorter  rod  is  attached  to  a  boss 
on  the  master  rod  by  a  short  pin  to  form  a  hinge  and  to 
permit  the  short  rod  to  oscillate  as  the  conditions  die- 


Connecting  Rod  Types 


311 


312 


Aviation  Engines 


tate.  This  form  of  rod  can  be  easily  adjusted  when  the 
bearing  depreciates,  a  procedure  that  is  .difficult  with  the 
forked  type  rod.  The  best  practice,  in  the  writer's  opin- 


Fig.  132.— Part  Sectional  View  of  Renault  Twelve-Cylinder  Water-Cooled 
Engine,  Showing  Connecting  Bod  Construction  and  Other  Important 
Internal  Parts. 

ion,  is  to  stagger  the  cylinders  and  use  side-by-side  rods 
as  is  done  in  the  Curtiss  engine.  Each  rod  may  be  fitted 
independently  of  the  other  and  perfect  compensation  for 
wear  of  the  big  ends  is  possible. 


Cam-Shaft  and  Crank-Shaft  Design  313 

CAM-SHAFT   AND    CRANK-SHAFT   DESIGN 

Before  going  extensively  into  the  subject  of  crank- 
shaft construction  it  will  be  well  to  consider  cam-shaft 
design,  which  is  properly  a  part  of  the  valve  system  and 
which  has  been  considered  in  connection  with  the  other 
elements  which  have  to  do  directly  with  cylinder  construc- 
tion to  some  extent.  Cam-shafts  are  usually  simple  mem- 
bers carried  at  the  base  of  the  cylinder  in  the  engine 
case  of  Vee  type  motors  by  suitable  bearings  and  having 
the  cams  employed  to  lift  the  valves  attached  at  intervals. 
A  typical  cam-shaft  design  is  shown  at  Fig.  133.  Two 
main  methods  of  cam-shaft  construction  are  followed — 


Bt 


Fig.    133.— Typical    Cam-Shaft,   with   Valve   Lifting   Cams    and   Gears   to 
Operate  Auxiliary  Devices  Forged  Integrally. 

that  in  which  the  cams  are  separate  members,  keyed  and 
pinned  to  the  shaft,  and  the  other  where .  the  cams  are 
formed  integral,  the  latter  being  the  most  suitable  for 
airplane  engine  requirements. 

The  cam-shafts  shown  at  Figs.  133  and  134,  B,  are  of 
the  latter  type,  as  the  cams  are  machined  integrally.  In 
this  case  not  only  the  cams  but  also  the  gears  used  in 
driving  the  auxiliary  shafts  are  forged  integral.  This  is 
a  more  expensive  construction,  because  of  the  .high  initial 
.cost  of  forging  dies  as  well  as  the  greater  expense  of 
machining.  It  has  ther  advantage  over  the  other  form  in 
which  the  cams  are  keyed  in  place  in  that  it  is  stronger, 
and  as  the  cams  are  a  part  of  the  shaft  they  can  never 
become  loose,  as  'might  be  possible  where  they  are  sepa- 
rately formed  and  assembled  on  a  simple  shaft. 

The  importance  of  the  crank-shaft  has  been  previously 


314 


Aviation  Engines 


considered,  and  some  of  its  forms  have  been  shown  in 
views  of  the  motors  presented  in  earlier  portions  of  this 
work.  The  crank-shaft  is  one  of  the  parts  subjected  to 
the  greatest  strain  and  extreme  care  is  needed  in  its  con- 


Fig.  134. — Important  Parts  of  Duesenberg  Aviation  Engine.  A — Three 
Main  Bearing  Crank-Shaft.  B — Cam-Shaft  with  Integral  Cams.  C — 
Piston  and  Connecting  Rod  Assembly.  D — Valve  Eocker  Group. 
E — Piston.  F — Main  Bearing  Brasses. 

struction  and  design,  because  practically  the  entire  duty 
of  transmitting  the  power  generated  by  the  motor  to  the 
gearset  devolves  upon  it.  Crank-shafts  are  usually  made 
of  high  tensile  strength  steel  of  special  composition.  They 
may  be  made  in  four  ways,  the  most  common  being  ,from 


Crank-Shaft  Construction 


315 


a  drop  or  machine  forging  which  is  formed  approximately 
to  the  shape  of  the  finished  shaft  and  in  rare  instances 
(experimental  motors  only)  they  may  be  steel  castings. 
Sometimes  they  are  made  from  machine  f  orgings,  where 
considerably  more  machine  work  is  necessary  than  would 
be  the  case  where  the  shaft  is  formed  between  dies. 
Some  engineers  favor  blocking  the  shaft  out  of  a  solid 
slab  of  metal  and  then  machining  this  rough  blank  to 
form.  In  some  radial-cylinder  motors  of  the  Gnome  and 


Fig.  135. — Showing  Method  of  Making  Crank-Shaft.  A — The  Rough  Steel 
Forging  Before  Machining.  B — The  Finished  Six-Throw,  Seven-Bear- 
ing Crank-Shaft. 

Le  Ehone  type  the  crank-shafts  are  built  up  of  two  pieces, 
held  together  by  taper  fastenings  or  bolts. 

The  form  of  the  shaft  depends  on  the  number  of 
cylinders  and  the  form  has  material  influence  on  the 
method  of  construction.  For  instance,  a  four-cylinder 
crank-shaft  could  be  made  by  either  of-  the  methods  out- 
lined. On  the  other  hand,  a  three-  or  six-cylinder  shaft 
is  best  made  by  the  machine  forging  process,  because  if 
drop  forged  or  cut  from  the  blank  it  will  have  to  be 
heated  and  the  crank  throws  bent  around  so  that  the  pins 
will  lie  in  three  planes  one  hundred  and  twenty  degrees 
apart,  while  the  other  types  described  need  no  further 
attention,  as  the  crank-pins  lie  in  planes  one  hundred 
and  eighty  degrees  apart.  This  can  be  better  understood 
by  referring  to  Fig.  135,  which  shows  a  six-cylinder  shaft 
in  the  rough  and  finished  stages.  At  A  the  appearance 


316 


Aviation  Engines 


of  the  machine  forging  before  any  of  the  material  is  re- 
moved is  shown,  while  at  B  the  appearance  of  the  finished 
crank-shaft  is  clearly  depicted.  The  built-up  crank-shaft 
is  seldom  used  on  multiple-cylinder  motors,  except  in 


Fig.    136.— Showing    Form    of    Crank-Shaft    for    Twin-Cylinder    Opposed 

Power  Plant. 

some  cases  where  the  crank-shafts  revolve  on  ball  bear- 
ings as  in  some  automobile  racing  engines. 

Crank-shaft  form  will  vary  with  a  number  of  cylinders 
and  it  is  possible  to  use  a  number  of  different  arrange- 
ments of  crank-pins  and  bearings  for  the  same  number 


Fig.   137. — Crank-Shaft  of.  Thomas-Morse  Eight-Cylinder  Vee  Engine. 

of  cylinders.  The  simplest  form  of  crank-shaft  is  that 
used  on  simple  radial  cylinder  motors  as  it  would  consist 
of  but  one  crank-pin,  .two  webs,  and  the  crank-shaft.  As 
the  number  of  cylinders  increase  in  Vee  motors  as  a  gen- 
eral rule  more  crank-pins  are  used.  The  crank- shaft  that 


Crank-Shaft  Construction 


317 


would  be  used  on  a  two-cylinder  opposed  motor  is  shown 
at  Fig.  136.  This  has  two  throws  and  the  crank-pins  are 
spaced  180  degrees  apart.  The  bearings  are  exception- 
ally long.  Four-cylinder  crank- shafts  may  have  two, 
three  or  five  main  bearings  and  three  or  four  crank-pins. 
In  some  forms  of  two-bearing  crank-shafts,  such  as  used 
when  four-cylinders  are  cast  in  a  block,  or  unit  casting, 


Fig.  138. — Crank-Case  and  Crank-Shaft  Construction  for  Twelve-Cylinder 
Motors.     A — Duesenberg.     B — Curtiss. 

two  of  the  pistons  are  attached  to  one  common  crank- 
pin,  so  that  in  reality  the  crank-shaft  has  but  three  crank- 
pins.  A  typical  three  bearing,  four-cylinder  crank-shaft 
is  shown  at  Fig.  134,  A.  The  same  type  can  be  used  for 
an  eight-cylinder  Vee  engine,  except  for  the  greater  length 
of  crank-pins  to  permit  of  side  by  side  rods  as  shown  at 
Fig.  137.  Six  cylinder  vertical  tandem  and  twelve-cylin- 
der Vee  engine  crank-shafts  usually  have  four  or  seven 
main  bearings  depending  upon  the  disposition  of  the 
crank-pins  and  arrangement  of  cylinders.  At  Fig.  138,  A, 


318 


Aviation  Engines 


the  bottom  view  of  a  twelve-cylinder  engine  with  bottom 
half  of  crank  case  removed  is  given.  This  illustrates 
clearly  the  arrangement  of  main  bearings  when  the  crank- 
shaft is  supported,  on  four  journals.  The  crank-shaft 
shown  at  Fig.  138,  B.  is  a  twelve-cylinder  seven-bearing 
type.  . 

In   some   automobile   engines,   extremely  good  results 
have  been  secured  in  obtaining  steady  running  with  mini- 


>Main  Bearing  No.  I 


/,  Balance  weights  forged 
/  \  integrally  with  shaft 


•  Main  Bearing  No.3 

n\ 


-.-Balance  weights  bolted  on 


Balance   weights- 


Fig.    139. — Counterbalanced    Crank-Shafts   Eeduce   Engine   Vibration   and 
Permit  of  Higher  Rotative  Speeds. 

mum  vibration  by  counterbalancing  the  crank-shafts  as 
outlined  at  Fig.  139.  The  shaft  at  A  is  a- type  suitable 
for  a  high  speed  four-cylinder  vertical  or  an  eight-cylin- 
der Vee  type.  That  at  B  is  for  a  six-cylinder  vertical  or 
a  twelve-cylinder  V  with  scissors  joint  rods.  If  counter- 
balancing crank-shafts  helps  in  an  automobile  engine,  it 
should  have  advantages  of  some  moment  in  airplane  en- 
gines, even  though  the  crank-shaft  weight  is  greater. 


B all-Bearing  Crank-Shafts  319 

BALL-BEARING   CRANK-SHAFTS 

While  crank-shafts  are  usually  supported  in  plain 
journals  there  seems  to  be  a  growing  tendency  of  late 
to  use  anti-friction  bearings  of  the  ball  type  for  their 
support.  This  is  especially  noticeable  on  block  motors 
where  but  two  main  bearings  are  utilized.  When  ball 
bearings  are  selected  with  proper  relation  to  the  load 
which  obtains  they  will  give  very  satisfactory  service. 
They  permit  the  crank- shaft  to  turn  with  minimum  fric- 
tion, and  if  properly  selected  will  never  need  adjustment. 
The  front  end  is  supported  by  a  bearing  which  is  clamped 
in  such  a  manner  that  it  will  take  a  certain  amount  of 
load  in  a  direction  parallel  to  the  axis  of  the  shaft,  while 
the  rear  end  is  so  supported  that  the  outer  race  of  the 
bearing  has  a  certain  amount  of  axial  freedom  or  "float." 
The  inner  race  or  cone  of  each  bearing  is  firmly  clamped 
against  shoulders  on  the  crank-shaft.  At  the  front  end 
of  the  crank- shaft  timing  gear  and  a  suitable  check  nut 
are  used,  while  at  the  back  end  the  bearing  is  clamped 
by  a  threaded  retention  member  between  the  fly-wheel 
and  a  shoulder  on  the  crank-shaft.  The  fly-wheel  is  held 
in  place  by  a  taper  and  key  retention.  The  ball  bearings 
are  carried  in  a  light  housing  of  bronze  or  malleable  iron, 
which  in  turn  are  held  in  the  crank-case  by  bolts.  The 
Kenault  engine  uses  ball  bearings  at  front  and  rear  ends 
of  the  crank-shaft,  but  has  plain  bearings  around  inter- 
mediate crank-shaft  journals.  The  rotary  engines  of  the 
Gnome,  Le  Rhone  and  Clerget  forms  would  not  be  prac- 
tical if  ball  bearings  were  not  used  as  the  bearing  fric- 
tion and  consequent  depreciation  would  be  very  high. 

ENGINE-BASE    CONSTRUCTION 

One  of  the  important  parts  of  the  power  plant  is  the 
substantial  casing  or  bed  member,  which  is  employed  to 
support  the  cylinders  and  crank-shaft  and  which  is  at- 
tached directly  to  the  fuselage  engine  supporting  mem- 


320  Aviation  Engines 

bers.  This  will  vary  widely  in  form,  but  as  a  general 
thing  it  is  an  approximately  cylindrical  member  which 
may  be  divided  either  vertically  or  horizontally  in  two 
or  more  parts.  Airplane  engine  crank-cases  are  usually 
made  of  aluminum,  a  material  which  has  about  the  same 
strength  as  cast  iron,  but  which  only  weighs  a  third  as 
much.  In  rare  cases  cast  iron  is  employed,  but  is  not 
favored  by  most  engineers  because  of  its  brittle  nature, 


Fig.  140. — View  of  Thomas  135  Horse-Power  Aeromotor,  Model  8,  Showing 
Conventional  Method  of  Crank-Case  Construction. 

great  weight  and  low  resistance  to  tensile  stresses.  Where 
exceptional  strength  is  needed  alloys  of  bronze  may  be 
used,  and  in  some  cases  where  engines  are  produced  in 
large  quantities  a  portion  of  the  crank-case  may  be  a 
sheet  steel  or  aluminum  stamping. 

Crank-cases  are  always  large  enough  to  permit  the 
crank-shaft  and  parts  attached  to  it  to  turn  inside  and 
obviously  its  length  is  determined  by  the  number  of  cylin- 
ders and  their  disposition.  The  crank-case  of  the  radial 
cylinder  or  double-opposed  cylinder  engine  would  be  sub- 
stantially the  same  in  length.  That  of  a  four-cylinder 


Crank-Case  Construction 


321 


will  vary  in  length  with  the  method  of  casting  the  cylin- 
der. When  the  four-cylinders  are  cast  in  one  unit  and 
a  two-bearing  crank-shaft  is  used,  the  crank-case  is  a  very 


Fig.  141. — Views  of  Upper  Half  of  Thomas  Aeromotor  Crank-Case. 

compact  and  short  member.  When  a  three-bearing  crank- 
shaft is  utilized  and  the  cylinders  are  cast  in  pairs,  the 
engine  base  is  longer  than  it  would  be  to  support  a  block 
casting,  but  is  shorter  than  one  designed  to  sustain  in- 


322 


Aviation  Engines 


dividual  cylinder  castings  and  a  five-bearing  crank-shaft. 
It  is  now  common  construction  to  cast  an  oil  container 
integral  with  the  bottom  of  the  engine  base  and  -to  draw 
the  lubricating  oil  from  it  by  means  of  a  pump,  as  shown 
at  Fig.  140.  The  arms  by  which  the  motor  is  supported 


Inlet  Ports 
Exhaust  Ports . 


Exhaust 


Right  Hand  Cylinder  Block 
Note:  Rigidity  andt  cleanliness  of  design 
also  central  inlet  port  locations 
for  even  distribution  of  gas 


Exhaust  Ports  r.. 


Inlet  Ports 
Exhaust  Ports  -A 


,(9/7  Duct  to  Cam  Shaft 

\    Bearing  and  Front 

Gear  Case 


''Crank  Shaft  Bearing 
Oil  Ports 


'Oil  Return  /y0fe .  Bearing  Supports 

Left  Hand  Cylinder  Block  Casting 


Fig.    142. — Method   of  Constructing  Eight-Cylinder  Vee   Engine,   Possible 
if  Aluminum  Cylinder  and  Crank-Case  Castings  are  Used. 


C rank-Case  Construction  323 

in  the  fuselage  are  substantial-ribbed  members  cast  inte- 
grally with  the  upper  half. 

The  approved  method  of  crank-case  construction  fa- 
vored by  the  majority  of  engineers  is  shown  at  the  top  of 
Fig.  141,  bottom  side  up.  The  upper  half  not  only  forms 
a  bed  for  the  cylinder  but  is  used  to  hold  the  crank-shaft 
as  well.  In  the  illustration,  the  three-bearing  boxes  form 
part  of  the  case,  while  the  .lower  brasses  are  in  the  form 


Fig.  143. — Simple  and  Compact  Crank-Case,  Possible  When  Radial  Cylinder 
Engine  Design  is  Followed. 

of  separately  cast  caps  retained  by  suitable  bolts.  In 
the  construction  outlined  the  bottom  part  of  the  case 
serves  merely  as  an  oil  container  and  a  protection  for 
the  interior,  mechanism  of  the  motor.  The  cylinders  are 
held  down  by  means  of  studs  screwed  into  the  crank-case 
top,  as  shown  at  Fig.  141,  lower  view.  If  the  aluminum 
cylinder  motor  has  any  future,  the  method  of  construc- 
tion outlined  at  Fig.  142,  which  has  been  used  in  cast  iron 
for  an  automobile  motor,  might  be  used  for  an  eight- 
cylinder  Vee  engine  for  airplane  use.  The  simplicity  of 
the  crank-case  needed  for  a  revolving  cylinder  motor 
and  its  small  weight  can  be  well  understood  by  examina- 
tion of  the  illustration  at  Fig.  143,  which  shows  the  en- 
gine crank-case  for  the  nine-cylinder  "Monosoupape" 
Gnome  engine.  This  consists"  of  two  accurately  machined 
forgings  held  together  by  bolts  as  clearly  indicated. 


CHAPTER   X 

Power  Plant  Installation— Curtiss  OX  2  Engine  Mounting  and  Operating 
Rules— Standard  S.  A.  E.  Engine  Bed  Dimensions — Hall-Scott 
Engine  Installation  and  Operation — Fuel  System  Rules — Ignition 
System — Water  System: — Preparations  to  Start  Engine — Mounting 
Radial  and  Rotary  Engines — Practical  Hints  to  Locate  Engine 
Troubles — All  Engine  Troubles  Summarized — Location  of  Engine 
Troubles  Made  Easy. 

The  proper  installation  of  the  airplane  power  plant 
is  more  important  than  is  generally  supposed,  as  while 
these  engines  are  usually  well  balanced  and  run  with  little 
vibration,  it  is  necessary  that  they  be  securely  anchored 
and  that  various  connections  to  the  auxiliary  parts  be 
carefully  made  in  order  to  prevent  breakage  from  vibra- 
tion and  that  attendant  risk  of  motor  stoppage  while  in 
the  air.  The  type  of  motor  to  be  installed  determines 
the  method  of  installation  to  be  followed.  As  a  general 
rule  six-cylinder  vertical  engine  and  eight-cylinder  Vee 
type  are  mounted  in  substantially  the  same  way.  The 
radial,  fixed  cylinder  forms  and  the  radial,  rotary  cylin- 
der Gnome  and  Ehone  rotary  types  require  an  entirely 
different  method  of  mounting.  Some  unconventional 
mountings  have  been  devised,  notably  that  shown  at  Fig. 
144,  which  is  a  six-cylinder  German  engine  that  is  in- 
stalled in  just  the  opposite  way  to  that  commonly  fol- 
lowed. The  inverted  cylinder  construction  is  not  gen- 
erally followed  because  even  with  pressure  feed,  dry 
crank-case  type  lubricating  system  there  is  considerable 
danger  of  over-lubrication  and  of  oil  collecting  and  car- 
bonizing in  the  combustion  chamber  and  gumming  up 
the  valve  action  much  quicker  than  would  be  the  case  if 
the  engine  was  operated  in  the  conventional  upright  posi- 
tion. The  reason  for  mounting  an  engine  in  this  way  is 
to  obtain  a  lower  center  of  gravity  and  also  to  make  for 

324 


Power  Plant  Installation 


325 


more  perfect  streamlining  of  the  front  end  of  the  fuselage 
in  some  cases.  It  is  rather  doubtful  if  this  slight  ad- 
vantage will  compensate  for  the  disadvantages  intro- 
duced by  this  unusual  construction.  It  is  not  used  to 
any  extent  now  but  is  presented  merely  to  show  one  of 
the  possible  systems  of  installing  an  airplane  engine. 

In  a  number  of  airplanes  of  the  tractor-biplane  type 
the  power  plant  installation  is  not  very  much  different 


r  i  — **•  •jk--,  \  » 

\  slk^^^^^^»>. !  /  / 


Fig.  144. — Unconventional  Mounting  of  German  Inverted  Cylinder  Motor. 


than  that  which  is  found  in  automobile  practice.  The 
illustration  at  Fig.  145-  is  a  very  clear  representation  of 
the  method  of  mounting  the  Curtiss  eight-cylinder  90 
H.  P.  or  model  0X2  engine  in  the  fuselage  of  the  Curtiss 
JN4  tractor  biplane  which  is  so  generally  used  in  the 
United  States  as  a  training  machine.  It  will  be  observed 
that  the  fuel  tank  is  mounted  under  a  cowl  directly  behind 
the  motor  and  that  it  feeds  the  carburetor  by  means  of  a 


326 


Aviation  Engines 


flexible  fuel  pipe.  As  the  tank  is  mounted  higher  than  the 
carburetor,  it  will  feed  that  member  by  gravity.  The 
radiator  is  mounted  at  the  front  end  of  the  fuselage  and 
connected  to  the  water  piping  on  the  motor  ,by  the  usual 
rubber  hose  connections.  An  oil  pan  is  placed  under  the 
engine  and  the  top  is  covered  with  a  hood  just  as  in 
motor  car  practice.  The  panels  of  aluminum  are  attached 


Fig.  145. — How  Curtiss  Model  OX2  Motor  is  Installed  in  Fuselage  of 
Curtiss  Tractor  Biplane.  Note  Similarity  of  Mounting  to  Automobile 
Power  Plant. 

to  the  sides  of  the  fuselage  and  are  supplied  with  doors 
which  open  and  provide  access  to  the  carburetor,  oil- 
gauge  and  other  parts  of  the  motor  requiring  inspection. 
The  complete  installation  with  the  power  plant  enclosed 
is  given  at  Fig.  146,  and  in  this  it  will  be  observed  that 
the  exhaust  pipes  are  connected  to  discharge  members 
that  lead  the  gases  above  the  top  plane.  In  the  engine 
shown  at  Fig.  145  the  exhaust  flows'  directly  into  the  air 
at  the  sides  of  the  machine  through  short  pipes  bolted  to 
the  exhaust  gas  outlet  ports.  The  installation  of  the 


c 


P 


327 


328 


Aviation  Engines 


radiator  just  back  of  the  tractor  screw  insures  that  ade- 
quate cooling  will  be  obtained  because  of  the  rapid  air 
flow  due  to  the  propeller  slip  stream. 

INSTALLATION   OF    CURTISS   OX  2    ENGINE 

The  following  instructions  are  given  in  the  Curtiss 
Instruction  Book  for  installing  the  0X2  engine  and  pre- 
paring it  for  flights,  and  taken  in  connection  with  the  very 


Flexible  Exhaust  Discharge  Pipes 


/r  Exhaust  Manifolds 

Radiator, 

\\ 


Fig.  147.— Front  View  of  L.  W.  F.  Tractor  Biplane  Fuselage,  Showing 
Method  of  Installing  Thomas  Aeromotor  and  Method  of  Disposing  of 
Exhaust  Gases. 


clear  illustration  presented  no  difficulty  should  be  experi- 
enced in  understanding  the  proper  installation,  and  mount- 
ing of  this  power  plant.  The  bearers  or  beds  should  be 
2  inches  wide  by  3  inches  deep,  preferably  of  laminated 
hard  wood,  and  placed  11%  inches  apart.  They  must  be 
well  braced.  The  six  arms  of  the  base  of  the  motor  are 


Curtis  OX2  Engine  Installation  329 

drilled  for  %-inch  bolts,  and  none  but  this  size  should 
be  used. 

1.  Anchoring  the  Motor.     Put  the  bolts  in  from  the 
bottom,  with  a  large  washer  under  the  head  of  each  so 
the  head  cannot  cut  into  the  wood.     On  every  bolt  use  a 
castellated  nut  and  a  cotter  pin,  or  an  ordinary  nut  and 
a  lock  washer,  so  the  bolt  will  not  work  loose.     Always 
set  motor  in  place  and  fasten  before  attaching  any  aux- 
iliary apparatus,  such  as  carburetor,  etc. 

2.  Inspecting   the   Ignition-Sivitch    Wires.     The   wires 
leading  from  the  ignition  switch  must  be  properly  con- 
nected— one  end  to  the  motor  body  for  ground,  and  the 
other  end  to  the  post  on  the  breaker  box  of  the  magneto. 

3.  Filling  the  Radiator.    Be  sure  that  the  water  from 
the  radiator  fills   the   cylinder  jackets.     Pockets    of  air 
may   remain   in   the    cylinder    jackets    even    though    the 
radiator  may  appear  full.     Turn  the  motor  over  a  few 
times  by  hand  after  filling  the  radiator,  and  then  add 
more  water  if  the  radiator  will  take  it.    The  air  pockets, 
if  allowed  to  remain,  may  cause  overheating  and  develop 
serious  trouble  when  the  motor  is  running. 

4.  Filling  the  Oil  Reservoir.     Oil  is  admitted  into  the 
crank-case  through  the  breather  tube  at  the  rear.     It  is 
well  to  strain  all  oil  put  into  the  crank-case.    In  filling  the 
oil  reservoir  be  sure  to  turn  the  handle  on  the  oil  sight- 
gauge  till  it  is  at  right  angles  with  the  gauge.     The  oil 
sight-gauge  is  on  the  side  of  the  lower  half  of  the  crank- 
case.     Put  in  about  3  gallons  of  the  best  obtainable  oil, 
Mobile   B   recommended.     It   is   important   to   remember 
that  the  very  best  oil  is  none  too  good. 

5.  Oiling  Exposed  Moving  Parts.     Oil  all  rocker-arm 
bearings  before  each  flight.    A  little  oil  should  be  applied 
where  the  push  rods  pass  through  the  stirrup  straps. 

6.  Filling   the    Gasoline    Tanks.     Be    certain   that    all 
connections  in  the  gasoline  system  are  tight. 

7.  Turning  on  the   Gasoline.     Open  the  cock  leading 
from  the  gasoline  tank  to  the  carburetor. 

8.  Charging  the  Cylinders.    With  the  ignition  switch 


330  Aviation  Engines 

OFF,  prime  the  motor  by  squirting  a  little  gasoline  in 
each  exhaust  port  and  then  turn  the  propeller  backward 
two  revolutions.  Never  open  the  exhaust  valve  by  oper- 
ating the  rocker-arm  by  hand,  as  the  push-rod  is  liable  to 
come  out  of  its  socket  in  the  cam  follower  and  bend  the 
rocker-arm  when  the  motor  turns  over. 

9.  Starting  the  Motor  Toy  Hand.     Always  retard  the 
spark  part  way,  to  prevent  back-firing,  by  pulling  for- 
ward the  wire  attached.  to  the  breaker  box.    Failure  to  so 
retard  the  spark  in  starting  may  result  in  serious  injury 
to  the  operator.    Turn  on  the  ignition  switch  with  throttle 
partly  open;  give  a  quick,  strong  pull  down  and  outward 
on  the  starting  crank  or  propeller.    As  soon  as  the  motor 
is  started  advance  the  spark  by  releasing  the  retard  wire. 

10.  Oil  Circulation.     Let  the  motor  run  at  low  speed 
for  a  few  minutes  in  order  to  establish  oil  circulation  in 
all  bearings.     With  all   parts   functioning   properly,   the 
throttle  may  be  opened  gradually  for  warming  up  before 
flight. 

*      STANDAKD    S.A.E.    ENGINE   BED   DIMENSIONS 

The  Society  of  Automotive  Engineers  have  made  ef- 
forts to  standardize  dimensions  of  bed  timbers  for  sup- 
porting power  plant  in  an  aeroplane.  Owing  to  the  great 
difference  in  length  no  standardization  is  thought  possible 
in  this  regard.  The  dimensions  recommended  are  as 
follows  : 

Distance  between  timbers  .......    12  in.          14  in.          16  in. 

Width  of  bed  timbers  ..........      1  %  in.        1  %  in.        2  in. 

Distance  between  centers  of  bolts.    IS1^  in.      15%  in.      18  in. 


It  will  be  evident  that  if  any  standard  of  this  nature 
were  adopted  by  engine  builders  that  the  designers  of 
fuselage  could  easily  arrange  their  bed  timbers  to  con- 
form to  these  dimensions,  whereas  it  would  be  difficult  to 
have  them  adhere  to  any  standard  longitudinal  dimen- 
sions which  are  much  more  easily  varied  in  fuselages 
than  the  transverse  dimensions  are.  It,  however,  should 


Standard  Engine  Bed  Dimensions 


331 


d Y 


332 


Aviation  Engines 


be  possible  to  standardize  the  longitudinal  positions  of 
the  holding  down  bolts  as  the  engine  designer  would  still 
be  able  to  allow  himself  considerable  space  fore-and-aft 
of  the  bolts. 

HALL-SCOTT   ENGINE   INSTALLATION 

The  very  thorough  manner  in  which  installation  dia- 
grams are  prepared  by  the  leading  engine  makers  leaves 
nothing  to  the  imagination.  The  dimensions  of  the  Hall- 
Scott  four-cylinder  airplane  engine  are  given  clearly  in 


Fig.  149.— Plan  and  Side  Elevation  of  HaU-Scott  A-7  Four-Cylinder  Air- 
plane  Engine,   with  Installation   Dimensions. 


Engine  Installation  333 

our  inch  measurements  with  the  metric  equivalents  at 
Figs.  148  and  149,  the  former  showing  a  vertical  eleva- 
tion while  the  latter  has  a  plan  view  and  side  elevation. 
The  installation  of  this  engine  in  airplanes  is  clearly 
shown  at  Figs.  150  and  151,  the  former  having  the  radi- 
ator installed  at  the  front  of  the  motor  and  having  all 
exhaust  pipes  joined  to  one  common  discharge  funnel, 


Fig.  150. 

CENSORED 


which  deflects  the  gas  ove'r  the  top  plane  while  the  latter 
has  the  radiator  placed  vertically  above  the  motor  at 
the  back  end  and  has  a  direct  exhaust  gas  discharge  to 
the  air. 

The  dimensions  of  the,  six-cylinder  Hall-Scott  motor 
which  is  known  as  the  type  A-5  125  H.  P.  are  given  at 
Fig.  152,  which  is  an  end  sectional  elevation,  and  at  Fig. 
153,  which  is  a  plan  view.  The  dimensions  are  given  both 
in  inch  sizes  and  the  metric  equivalents.  The  appearance 


334  Aviation  Engines 

of  a  Hall-Scott  six-cylinder  engine  installed  in  a  fuselage 
is  given  at  Fig.  154,  while  a  diagram  showing  the  loca- 
tion of  the  engine  and  the  various  pipes  leading  to  the 
auxiliary  groups  is  outlined  at  Fig.  155.  The  following 
instructions  for  installing  the  Hall-Scott  power  plant  are 


Fig.  151. 

CENSORED 


Engine  Installation  335 


Fig.  152. 

CENSORED 


336 


Aviation  Engines 


reproduced  from  the  instruction  book  issued  by  the  maker. 
Operating  instructions  which  are  given  should  enable  any 
good  mechanic  to  make  a  proper  installation  and  to  keep 
the  engine  in  good  running  condition. 


FUEL   SYSTEM   INSTALLATION 


Gasoline  giving  the  best  results  with  this  equipment 
is  as  follows:  Gravity  58-62  deg.  Baume  A.  Initial  boil- 
ing point — Eichmond  method — 102°  Fahr.  Sulphur  .014. 


"  -A*-- 6'/z"-*#"6'/2"~l\ 

•"*•    I/I  /6£«*- J/1/65MW.J/ 


Fig.  153.— Plan  View  of  Hall-Scott  Type  A-5  125  Horse-Power  Airplane 
Engine,  Showing  Installation  Dimensions. 

Calorimetric  bomb  test  20610  B.  T.  IL  per  pound.  If  the 
gasoline  tank  is  placed  in  the  fuselage  below  the  level  of 
the  carburetor,  a  hand  pump  must  be  used  to  maintain 
air  pressure  in  gas  tank  to  force  the  gasoline  to  the  car- 
buretor. After  starting  the  engine  the  small  auxiliary  air 
pump  upon  the  engine  will  maintain  sufficient  pressure. 
A-7a  and  A-5a  engines  are  furnished  with  a  new  type 
auxiliary  air  pump.  This  should  be  frequently  oiled  and 
care  taken  so  no  grit  or  sand  will  enter  which  might  lodge 
between  the  valve  and  its  seat,  which  would  make  it  fail 
to  operate  properly.  An  air  relief  valve  is  furnished  with 
each  engine.  It  should  be  screwed  into  the  gas  tank  and 
properly  regulated  to  maintain  the  pressure  required. 


Hall-Scott  Engine  Installation 


337 


This  is  done  by  screwing  the  ratchet  on  top  either  up  or 
down.  If  two  tanks  are  used  in  a  plane  one  should  be 
installed  in  each  tank.  All  air  pump  lines  should  be  care- 


Fig.  154.— Three-Quarter  View  of  Hall-Scott  Type  A-5  125  Horse-Power 
Six-Cylinder  Engine,  with  One  of  the  Side  Radiators  Removed  to 
Show  Installation  in  Standard  Fuselage. 


338 


Engine  Installation  339 

fully  gone  over  quite  frequently  to  ascertain  if  they  are 
tight.  Check  values  have  to  be  placed  in  these  lines.  In 
some  cases  the  gasoline  tank  is  placed  above  the  engine, 
allowing  it  to  drain  by  gravity  to  the  carburetor.  When 
using  this  system  there  should  be  a  drop  of  .not  less  than 
two  feet  from  the  lowest  portion  of  the  gasoline  tank  to 
the  upper  part  of  the  carburetor  float  chamber.  Even 
this  height  might  not  be  sufficient  to  maintain  the  proper 
volume  of  gasoline  to  the  carburetor  at  high  speeds.  Air 
pressure  is  advised  upon  all  tanks  to  insure  the  proper 
supply  of  gasoline.  When  using  gravity  feed  without 
air  pressure  be  sure  to  vent  the  tank  to  allow  circulation 
of  air.  If  gravity  tank  is  used  and  the  engine  runs  satis- 
factorily at  low  speeds  but  cuts  out  at  high  speeds  the 
trouble  is  undoubtedly  due  to  insufficient  height  of  the 
tank  above  the  carburetor.  The  tank  should  be  raised  or 
air  pressure  system  used. 

IGNITION    SWITCHES 

Two  " DIXIE"  switches  are  furnished  with  each  en- 
gine. Both  of  these  should  be  installed  in  the  pilot's 
seat,  one  controlling  the  E.  H.,  and  the  other  the  L.  H. 
magneto.  By  shorting  either  one  or  the  other  it  can  be 
quickly  determined  if  both  magnetos,  with  their  respec- 
tive spark-plugs,  are  working  correctly.  Care  should  be 
taken  not  to  use  spark-plugs  having  special  extensions  or 
long  protruding  points.  Plugs  giving  best  results  are  ex- 
tremely small  with  short  points. 

WATER   SYSTEMS 

A  temperature  gauge  should  be  installed  in  the  water 
pipe,  coming  directly  from  the  cylinder  nearest  the  pro- 
peller (note  illustration  above).  This  instrument  in- 
stalled in  the  radiator  cap  has  not  always  given  satis- 
factory results.  This  is  especially  noticeable  when  the 
water  in  the  radiator  becomes  low,  not  allowing  it  to 
touch  the  bulb  on  the  moto-meter.  For  ordinary  running, 


340  Aviation  Engines 

it  should  not  indicate  over  150  degrees  Fahr.  In  climb- 
ing tests,  however,  a  temperature  of  160  degrees  Fahr. 
can  be  maintained  without  any  ill  effects  upon  the  en- 
gine. In  case  the  engine  becomes  overheated,  the  indi- 
cator will  register  above  180  degrees  Fahr.,  in  which  case 
it  should  be  stopped  immediately.  Overheating  is  most 
generally  caused  by  retarded  spark,  excessive  carbon  in 
the  cylinders,  insufficient  lubrication,  improperly  timed 
valves,  lack  of  water,  clogging  of  water  system  in  any 
way  which  would  obstruct  the  free  circulation  of  the 
water. 

Overheating  will  cause  the  engine  to  knock,  with  pos- 
sible damaging  results.  Suction  pipes  should  be  made 
out  of  thin  tubing,  and  run  within  a  quarter  or  an  eighth 
of  an  inch  of  each  other,  so  that  when  a  hose  is  placed 
over  the  two,  it  will  not  be  possible  to  suck  together. 
This  is  often  the  case  when  a  long  rubber  hose  is  used, 
which  causes  overheating.  Eadiators  should  be  flushed 
out  and  cleaned  thoroughly  quite  often.  A  dirty  radiator 
may  cause  overheating. 

When  filling  the  radiator  it  is  very  important  to  re- 
move the  plug  on  top  of  the  water  pump  until  water 
appears.  This  is  to  avoid  air  pockets  being  formed  in  the 
circulating  system,  which  might  not  only  heat  up  the 
engine,  but  cause  considerable  damage.  All  water  pump 
hoses  and  connections  should  be  tightly  taped  and  shel- 
lacked after  the  engine  is  properly  installed  in  the  plane. 
The  greatest  care  should  be  taken  when  making  engine 
installation  not  to  •  use  .  smaller  inside  diameter  hose  con- 
nection than  water  pump  suction  end  casting.  One  inch 
and  a  quarter  inside  diameter  should  be  used  on  A-7  and 
A-5  motors,  while  nothing  less  than  one  inch  and  a  half 
inside  diameter  hose  or  tubing  on  all  A-7a  and  A-5a  en- 
gines. It  is  further  important  to  have  light  spun  tubing, 
void  of  any  sharp  turns,  leads  from  pump  to  radiator  and 
cylinder  water  outlet  to  radiator.  In  other  words,  the 
water  circulation  through  the  engine  must  be  as  little 
restricted  as  possible.  Be  sure  no  light  hose  is  used,  that 


Preparations  to  Start  Engine  341 

will  often  suck  together  when  engine  is  started.  To  thor- 
oughly drain  the  water  from  the  entire  system,  open  the 
drain  cock  at  the  lowest  side  of  the  water  pump. 

PREPARATIONS   TO    START    ENGINE 

Always  replenish  gasoline  tanks  through  a  strainer 
which  is  clean.  This  strainer  must  catch  all  water  and 
other  impurities  in  the  gasoline.  Pour  at  least  three 
gallons  of  fresh  oil  into  the  lower  crank-case.  Oil  all 
rocker  arms  through  oilers  upon  rocker  arm  housing  caps. 
Be  sure  radiators  are  filled  within  one  inch  of  the  top. 

After  all  the  parts  are  oiled,  and  the  tanks  filled,  the 
following  must  be  looked  after  before  starting:  See  if 
crank-shaft  flange  is  tight  on  shaft.  See  if  propeller  bolts 
are  tight  and  evenly  drawn  up.  See  if  propeller  bolts  are 
wired.  See  if  propeller  is  trued  up  tp  within  %". 

Every  four  days  the  magnetos  should  be  oiled  if  the 
engine  is  in  daily  use. 

Every  month  all  cylinder  hold-down  nuts  should  be 
gone  over  to  ascertain  if  they  are  tight.  (Be  sure  to  re- 
cotter  nuts.) 

See  if  magnetos  are  bolted  on  tight  and  wired. 

See  if  magneto  cables  are  in  good  condition. 

See  if  rocker  arm  tappets  have  a  .020"  clearance  from 
valve  stem  when  valve  is  seated. 

See  if  tappet  clamp  screws  are  tight  and  cottered. 

See  if  all  gasoline,  oil,  water  pipes  and  connections  are 
in  perfect  condition. 

Air  on  gas  line  should  be  tested  for  leaks. 

Pump  at  least  three  pounds  air  pressure  into  gasoline 
tank. 

After  making  sure  that  above  rules  have  been  ob- 
served, test  compression  of  cylinders  by  turning  propeller. 

"DO    NOT   FORGET   TO    SHORT   BOTH    MAGNETOS  " 

Be  sure  all  compression  release  and  priming  cocks  do 
not  leak  compression.  If  they  do,  replace  same  with  a 


342  Aviation  Engines 

new  one  immediately,  as  this  might  cause  premature 
firing. 

Open  priming  cocks  and  squirt  some  gasoline  into  each. 

Close  cocks. 

Open  compression  release  cocks. 

Open  throttle  slightly. 

If  using  Berling  magnetos  they  should  be  three-quar- 
ters advanced. 

If  all  the  foregoing  directions  have  been  carefully 
followed,  the  engine  is  ready  for  starting. 

In  cranking  engine  either  by  starting  crank,  or  pro- 
peller, it  is  essential  to  throw  it  over  compression  quickly. 

Immediately  upon  starting,  close  compression  release 
cocks. 

When  engine  is  running,  advance  magnetos. 

After  it  has  warmed  up,  short  one  magneto  and  then 
the  other,  to  be  sure  both  magnetos  and  spark-plugs  are 
firing  properly.  If  there  is  a  miss,  the  fouled  plug  must 
be  located  and  cleaned.  There  is  a  possibility  that  the 
jets  in  the  carburetor  are  stopped  up.  If  this  is  the  case, 
do  not  attempt  to  clean  same  with  any  sharp  instrument. 
If  this  is  done,  it  might  change  the  opening  in  the  jets, 
thus  spoiling  the  adjustment.  Jets  and  nozzles  should 
be  blown  out  with  air  or  steam. 

An  open  intake  or  exhaust  valve,  which  might  have 
become  sluggish  or  stuck  from  carbon,  might  cause 
trouble.  Be  sure  to  remedy  this  at  once  by  using  a  little 
coal-oil  or  kerosene  on  same,  working  the  valve  by  hand 
until  it  becomes  free.  We  recommend  using  graphite  on 
valve  stems  mixed  with  oil  to  guard  against  sticking  or 
undue  wear. 


INSTALLING  ROTARY  AND   RADIAL   CYLINDER  ENGINES 

When  rotary  engines  are  installed  simple  steel  stamp- 
ing or  "spiders"  are  attached  to  the  fuselage  to  hold  the 
fixed  crank-shaft.  Inasmuch  as  the  motor  projects  clear 
of  the  fuselage  proper  there  is  plenty  of  room  back  of 


|i 


II 

ll 

II 

«M      W 
|S 


343 


344 


Aviation  Engines 


the  front  spider  plate  to  install  the  auxiliary  parts  such 
as  the  oil  pump,  air  pump  and  ignition  magneto  and  also 
the  fuel  and  oil  containers.  The  diagram  given  at  Fig. 
156  shows  how  a  Gnome  "monosoupape"  engine  is  in- 
stalled on  the  anchorage  plates  and  it  also  outlines  clearly 
the  piping  necessary  to  convey  the  oil  and  fuel  and  also 
the  air-piping  needed  to  put  pressure  on  both  fuel  and 
oil  tanks  to  insure  positive  supply  of  these  liquids  which 


:• — Air  Screw 


Motor  in 
Front 


Tractor  Screw — 
in  Front 


*'Motor  in  Rear 


B 


Fig.   157. — Showing  Two  Methods  of  Placing  Propeller  on  Gnome  Rotary 

Motor. 

may  be  carried  in  tanks  placed  lower  than  the  motor  in 
some  installations.  The  diagram  given  at  Figs.  157  and 
158  shows  other  mountings  of  Gnome  engines  and  are 
self-explanatory.  The  simple  mounting  possible  when  the 
Anzani  ten-cylinder  radial  fixed  type  engine  is  used  given 
at  Fig.  159.  The  front  end  of  the  fuselage  is  provided 
with  a  substantial  pressed  steel  plate  having  members 
projecting  from  it  which  may  be  bolted  to  the  longer- 
ons. The  bolts  that  hold  the  two  halves  of  the  crank- 
case  together  project  through  the  steel  plate  and  hold  the 
engine  securely  to  the  front  end  of  the  fuselage. 


Location  of .  Engine  Troubles 


345 


PRACTICAL    HINTS    TO    LOCATE    ENGINE    TROUBLES 

One  who  is  not  thoroughly  familiar  with  engine  con- 
struction will  seldom  locate  troubles  by  haphazard  experi- 
menting and  it  is  only  by  a  systematic  search  that  the 
cause  can  be  discovered  and  the  defects  eliminated.  In 
this  chapter  the  writer  proposes  to  outline  some  of  the 
most  common  power-plant  troubles  and  to  give  sufficient 


Upper 
Longeron 


'Front  Engine 
•Upper  Support 

^  Longerons-,^ 


Rear  Engine  Support 
.Crank-Shaft 

^= 
'Carburetor" 


••Tractor  Screw 

Side  View 


'-Lower 
Longeron 


*~- Lower  Longerons-' 
Front  View 


Fig.    158. — How    Gnome    Eotary    Motor    May    Be    Attached    to    Airplane 

Fuselage  Members. 

advice  to  enable  those  who  are  not  thoroughly  informed 
to  locate  them  by  a  logical  process  of  elimination.  The 
internal-combustion  motor,  which  is  the  power  plant  of 
all  gasoline  automobiles  as  well  as  airplanes,  is  composed 
of  a  number  of  distinct  groups,  which  in  turn  include  dis- 
tinct components.  These  various  appliances  are  so  closely 
related  to  each  other  that  defective  action  of  any  one  may 
interrupt  the  operation  of  the  entire  power  plant.  Some 
of  the  auxiliary  groups  are  more  necessary  than  others 
and  the  power  -plant  will  continue  to  operate  for  a  time 
even  after  the  failure  of  some  important  parts  of  some 
of  the  auxiliary  groups.  The  gasoline  engine  in  itself  is 


346 


Aviation  Engines 


a  complete  mechanism,  but  it  is  evident  that  it  cannot 
deliver  any  power  without  some  means  of  supplying  gas 
to  the  cylinders  and  igniting  the  compressed  gas  charge 
after  it  has  been  compressed  in  the  cylinders.  From  this 


Fixed  Cylinder 
Radial  Engine 


Engine        \ 
Supporting  J~ 
P/ai-e         ) 


Fig.  159. — How  Anzani  Ten-Cylinder  Eadial  Engine  is  Installed  to  Plate 
Securely  Attached  to  Front  End  of  Tractor  Airplane  Fuselage. 


Typical  Engine  Stoppage  Analyzed  347 

it  is  patent  that  the  ignition  and  carburetion  systems  are 
just  as  essential  parts  of  the  power  plant  as  the  piston, 
connecting  rod,  or  cylinder  of  the  motor.  The  failure  of 
either  the  carburetor  or  igniting  means  to  function  prop- 
erly will  be  immediately  apparent  by  faulty  action  of  the 
power  plant. 

To  insure  that  the  motor  will  continue  to  operate  it 
is  necessary  to  keep  it  from  overheating  by  some  form  of 
cooling  system  and  to  supply  oil  to  the  moving  parts  to 
reduce  friction.  The  cooling  and  lubrication  groups  are 
not  so  important  as  carburetion  and  ignition,  as  the  en- 
gine would  run  for  a  limited  period  of  time  even  should 
the  cooling  system  fail  or  the  oil  supply  cease.  It  would 
only  be  a  few  moments,  however,  before  the  engine  would 
overheat  if  the  cooling  system  was  at  fault,  and  the  parts 
seize  if  the  lubricating  system  should  fail.  Any  derange- 
ment in  the  carburetor  or  ignition  mechanism  would  man- 
ifest itself  at  once  because  the  engine  operation  would  be 
affected,  but  a  defect  in  the  cooling  or  oiling  system  would 
not  be  noticed  so  readily. 

The  careful  aviator  will  always  inspect  the  motor 
mechanism  before  starting  on  a  trip  of  any  consequence, 
and  if  inspection  is  carefully  carried  out  and  loose  parts 
tightened  it  is  seldom  that  irregular  operation  will  be 
found  due  to  actual  breakage  of  any  of  the  components 
of  the  mechanism.  Deterioration  due  to  natural  causes 
matures  slowly,  and  sufficient  warning  is  always  given 
when  parts  begin  to  wear  so  satisfactory  repairs  may  be 
promptly  made  before  serious  derangement  or  failure  is 
manifested. 


A   TYPICAL   ENGINE    STOPPAGE   ANALYZED 

Before  describing  the  points  that  may  fail  in  the  vari- 
ous auxiliary  systems  it  will  be  well  to  assume  a  typical 
case  of  engine  failure  and  show  the  process  of  locating 
the  trouble  in  a  systematic  manner  by  indicating  the 
various  steps  which  are  in  logical  order  and  which  could 


348 


Aviation  Engines 


reasonably  be  followed.  In  any  case  of  engine  failure  the 
ignition  system,  motor  compression,  and  carburetor  should 
be  tested  first.  If  the  ignition  system  is  functioning  prop- 
erly one  should  determine  the  amount  of  compression  in 
all  cylinders  and  if  this  is  satisfactory  the  carbureting 
group  should  be  tested.  If  the  ignition  system  is  working 
properly  and  there  is  a  decided  resistance  in  the  cylinders 


UJ  LJ  LJ 

"-assas.  35-~** 


Fig.   160. — Side   Elevation  of   Thomas   135   Horse-Power  Airplane   Engine, 
Giving  Important  Dimensions. 

when  the  propeller  is  turned,  proving  that  there  is  good 
compression,  one  may  suspect  the  carburetor. 

If  the  carburetor  appears  to  be  in  good  condition,  the 
trouble  may  be  caused  by  the  ignition  being  out  of  time, 
which  condition  is  possible  when  the  magneto  timing  gear 
or  coupling  is  attached  to  the  armature  shaft  by  a  taper 
and  nut  retention  instead  of  the  more  positive  key  or 
taper-pin  fastening.  It  is  possible  that  the  inlet  manifold 
may  be  broken  or  perforated,  that  the  exhaust  valve  is 
stuck  on  its  seat  because  of  a  broken  or  bent  stem,  broken 
or  loose  cam,  or  failure  of  the  cam-shaft  drive  because 
the  teeth  are  stripped  from  the  engine  shaft  or  cam-shaft 


Engine  Troubles  Summarized 


349 


gears;  'or  because  the  key  or  other  fastening  on  either 
gear  has  failed,  allowing  that  member  to  turn  independ- 
ently of  the  shaft  to  which  it  normally  is  attached.  The 
gasoline  feed  pipe  may  be  clogged  or  broken,  the  fuel 


Fig.  161. — Front  Elevation  of  Thomas-Morse  135  Horse-Power  Aeromotor, 
Showing  Main  Dimensions. 

supply  may  be  depleted,  or  the  shut-off  cock  in  the  gaso- 
line line  may  have  jarred  closed.  The  gasoline  filter  may 
be  filled  with  dirt  or  water  which  prevents  passage  of  the 
fuel. 

The  defects  outlined  above,  except  the  failure  of  the 


350  Aviation  Engines 

gasoline  supply,  are  very  rare,  and  if  the  container  is 
found  to  contain  fuel  and  the  pipe  line  to  be  clear  to  the 
carburetor,  it  is  safe  to  assume  the  vaporizing  device  is 
at  fault.  If  fuel  continually  runs  out  of  the  mixing  cham- 
ber 'the  carburetor  is  said  to  be  flooded.  This  condition 
results  from  failure  of  the  shut-off  needle  to  seat  properly 
or  from  a  punctured  hollow  metal  float  or  a  gasoline- 
soaked  cork  float.  It  is  possible  that  not  enough  gasoline 
is  present  in  the  float  chamber.  If  the  passage  controlled 
by  the  float-needle  valve  is  clogged  or  if  the  float  was 
badly  out  of  adjustment,  this  contingency  would  be  prob- 
able. When  the  carburetor  is  examined,  if  the  gasoline 
level  appears  to  be  at  the  proper  height,  one  may  suspect 
that  a  particle  of  lint,  or  dust,  or  fine  scale,  or  rust  from 
the  gasoline  tank  has  clogged  the  bore  of  the  jet  in  the 
mixing  chamber. 

If  the  ignition  system  and  carburetor  appear  to  be  in 
good  working  order,  and  the  hand  crank  shows  that  there 
is  no  compression  in  one  or  more  of  the  cylinders,  it 
means  some  defect  in  the  valve  system.  If  the  engine  is 
a  multiple-cylinder  type  and  one  finds  poor  compression 
in  all  of  the  cylinders  it  may  be  due  to  the  rare  defect 
of  improper  valve  timing.  This  may  be  caused  by  a  gear 
having  altered  its  position  on  the  cam-shaft  or  crank- 
shaft, because  of  a  sheared  key  or  pin  having  permitted 
the  gear  to  turn  about  half  of  a  revolution  and  then 
having  caught  and  held  the  gear  in  place  by  a  broken  or 
jagged  end  so  that  cam-shaft  would  turn,  but  the  valves 
open  at  the  wrong  time.  If  but  one  of  the  cylinders  is 
at  fault  and  the  rest  appear  to  have  good  compression 
the  trouble  may  be  due  to  a  defective  condition  either  in- 
side or  outside  of  that  cylinder.  The  external  parts  may 
be  inspected  easily,  so  the  following  should  be  looked  for : 
a  broken  valve,  a  warped  valve-head,  broken  valve-springs, 
sticking  or  bent  valve-stems,  dirt  under  valve-seat,  leak 
at  valve-chamber  cap  or  spark-plug  gasket.  .Defective 
priming  cock,  cracked* cylinder  head  (rarely  occurs),  leak 
through  cracked  spark  -  plug  insulation,  valve  -  plunger 


bO 


I 


351 


352  Aviation  Engines 

stuck  in  the  guide,  lack  of  clearance  between  valve-stem 
end  and  top  of  plunger  caused  by  loose  adjusting  screw 
which  has  worked  up  and  kept  the  valve  from  seating. 
The  faulty  compression  may  be  due  to  defects  inside  the 
motor.  The  piston-head  may  be  cracked  (rarely  occurs), 
piston  rings  may  be  broken,  the  slots  in  the  piston  rings 
may  be  in  line,  the  rings  may  have  lost  their  elasticity 
or  have  become  gummed  in  the  groves  of  the  piston,  or 
the  piston  and  cylinder,  walls  may  be  badly  scored  by  a 
loose  wrist  pin  or  by  defective  lubrication.  If  the  motor 
is  a  type  with  a  separate  head  it  is  possible  the  gasket 
or  packing  between  the  cylinder  and  combustion  chamber 
may  leak,  either  admitting  water  to  the  cylinder  or  allow- 
ing compression  to  escape. 

CONDITIONS    THAT    CAUSE    FAILURE    OF   IGNITION    SYSTEM 

If  the  first  test  of  the  motor  had  showed  that  the  com- 
pression was  as  it  should  be  and  that  there  were  no  seri- 
ous mechanical  defects  and  there  was  plenty  of  gasoline 
at  the  carburetor,  this  would  have  demonstrated  that  the 
ignition  system  was  not  functioning  properly.  If  a  bat- 
tery is  employed  to  supply  current  the  first  step  is  to  take 
the  spark-plugs  out  of  the  cylinders  and  test  the  system 
by  turning  over  the  engine  by  hand.  If  there  is  no  spark 
in  any  of  the  plugs,  this  may  be  considered  a  positive 
indication  that  there  is  a  broken  main  current  lead  from 
the  battery,  a  defective  ground  connection,  a  loose  bat- 
tery terminal,  or  a  broken  connector.  If  none  of  these 
conditions  are  present,  it  is  safe  to  say  that  the  battery 
is  no  longer  capable  of  delivering  current.  While  mag- 
neto ignition  is  generally  used  on  airplane  engines,  there 
is  apt  to  be  some  development  of  battery  ignition,  espe- 
cially on  engines  equipped  with  electric  self-starters  which 
are  now  being  experimented  with.  The  spark-plugs  may 
be  short  circuited  by  cracked  insulation  or  carbon  and 
oil  deposits  around  the  electrode.  The  secondary  wires 
may  be  broken  or  have  defective  insulation  which  permits 


Ignition  System  Failure  353 

the  current  to  ground  to  some  metal  part  of  the  fuselage 
or  motor.  The  electrodes  of  the  spark-plug  may  be  too 
far  apart  to  permit  a  spark  to  overcome  the  resistance 
of  the  compressed  gas,  even  if  a  spark  jumps  the  air 
space,  when  the  plug  is  laid  on  the  cylinder. 

If  magnetos  are  fitted  as  is  usually  the  case  at  present 
and  a  spark  is  obtained  between  the  points  of  the  plug 
and  that  device  or  the  wire  leading  to  it  from  the  magneto 
is  in  proper  condition,  the  trouble  is  probably  caused  by 
the  magneto  being  out  of  time.  This  may  result  if  the 
driving  gear  is  loose  on  the  armature-shaft  or  crank- 
shaft, and  is  a  rare  occurrence.  If  no  spark  is  produced 
at  the  plugs  the  secondary  wire  may  be  broken,  the  ground 
wire  may  make  contact  with  some  metallic  portion  of  the 
chassis  before  it  reaches  the  switch,  the  carbon  collecting 
brushes  may  be  broken  or  not  making  contact,  the  contact 
points  of  the  make-and-break  device  may  be  out  of  adjust- 
ment, the  wiring  may  be  attached  to  wrong  terminals,  the 
distributor  filled  with  metallic  particles,  carbon,  dust  or 
oil  accumulations,  the  distributor  contacts  may  not  be 
making  proper  connection  because  of  wear  and  there  may 
be  a  more  serious  derangement,  such  as  a  burned  out 
secondary  winding  or  a  punctured  condenser. 

If  the  motor  runs  intermittently,  i.e.,  starts  and  runs 
only  a  few  revolutions,  aside  from  the  conditions  pre- 
viously outlined,  defective  operation  may  be  due  to  seiz- 
ing between  parts  because  of  insufficient  oil  or  deficient 
cooling,  too  much  oil  in  the  crank-case  which  fouls  the 
cylinder  after  the  crank-shaft  has  revolved  a  few  turns, 
and  derangements  in  the  ignition  or  carburetion  systems 
that  may  be  easily  remedied.  There  are  a  number  of 
defective  conditions  which  may  exist  in  the  ignition  group, 
that  will  result  in  "skipping"  or  irregular  operation  and 
the  following  points  should  be  considered  first:  weak 
source  of  current  due  to  worn  out  dry  cells  or  discharged 
storage  batteries;  weak  magnets  in  magneto,  or  defective 
contacts  at  magneto;  dirt  in  magneto  distributor  or  poor 
contact  at  collecting  brushes.  Dirty  or  cracked  insulator 


356  Aviation  Engines 

justed  and  the  mixture  delivered  the  cylinder  burns  prop- 
erly, the  exhaust  gas  will  be  clean  and  free  from  .the 
objectionable  odor  present  when  gasoline  is  burned  in 
excess. 

The  character  of  combustion  may  be  judged  by  the 
color  of  the  flame  which  issues  from  it  when  the  engine 
is  running  with  an  open  throttle  after  nightfall.  If  the 
flame  is  red,  it  indicates  too  much  gasoline.  If  yellowish, 
it  shows  an  excess  of  air,  while  a  properly  proportioned 
mixture  will  be  evidenced  by  a  pronounced  blue  flame, 
such  as  given  by  a  gas-stove  burner. 

The  Duplex  Model  0.  D.  Zenith  carburetor  used  upon 
most  of  the  six-  and  eight-cylinder  airplane  engines  con- 
sists of  a  single  float  chamber,  and  a  single  air  intake, 
joined  to  two  separate  and  distinct  spray  nozzles,  venturi 
and  idling  adjustments.  It  is  to  be  noted  that  as  the 
carburetor  barrels  are  arranged  side  by  side,  both  valves 
are  mounted  on  the  same  shaft,  and  work  in  unison 
through  a  single  operating  lever.  It  is  not  necessary  to 
alter  their  position.  In  order  to  make  the  engine  idle 
well,  it  is  essential  that  the  ignition,  especially  the  spark- 
plugs, should  be  in  good  condition.  The  gaskets  between 
carburetor  and  manifold,  and  between  manifold  and  cylin- 
ders should  be  absolutely  air-tight.  •  The  adjustment  for 
low  speed  on  the  carburetor  is  made  by  turning  in  or  out 
the  two  knurled  screws,  placed  one  on  each  side  of  the 
float  chamber.  After  starting  the  engine  and  allowing  it 
to  become  thoroughly  warmed,  one  side  of  the  carburetor 
should  be  adjusted  so  that  the  three  cylinders  it  affects 
fire  properly  at  low  speed.  The  other  side  should  be 
adjusted  in  the  same  manner  until  all  six  cylinders  fire 
perfectly  at  low  speed.  As  the  adjustment  is  changed 
on  the  knurled  screw  a  difference  in  the  idling  of  the  en- 
gine should  be  noticed.  If  the  engine  begins  to  run  evenly 
or  speeds  up  it  shows  that  the  mixture  becomes  right  in 
its  proportion. 

Be  sure  the  butterfly  throttle  is  closed  as  far  as  pos- 
sible by  screwing  out  the  stop  screw  which  regulates  the 


Zenith  Carburetor  Adjustments  357 

closed  position  for  Idling.  Care  should  be  taken  to  have 
the  butterfly  held  firmly  against  this  stop  screw  at  all 
times  while  idling  engine.  If  three  cylinders  seem  to  run 
irregularly  after  changing  the  position  of  the  butterfly, 
still  another  adjustment  may  have  to  be  made  with  the 
knurled  screw.  Unscrewing  this  makes  the  mixture 
leaner.  Screwing  in  closes  off  some  of  the  air  supply  to 
the  idling  jet,  making  it  richer.  After  one  side  has  been 
made  to  idle  satisfactorily  repeat  the  same  procedure  with 
the  opposite  three  cylinders.  In  other  words,  each  side 
should  be  idled  independently  to  about  the  same  speed. 
Eemember  that  the  main  jet  and  compensating  jet 
have  no  appreciable  effect  on  the  idling  of  the  engine. 
The  idling  mixture  is  drawn  directly  through  the  opening 
determined  by  the  knurled  screw  and  enters  the  car- 
buretor barrel  through  the  small  hole  at  the  edge  of  each 
butterfly.  This  is  called  the  priming  hole  and  is  only 
effective  during  idling.  Beyond  that  point  the  suction  is 
transferred  to  the  main  jet  and  compensator,  which  con- 
trols the  power  of  the  engine  beyond  the  idling  position 
of  the  throttle. 

DEFECTS    IN    OILING    SYSTEMS 

While  troubles  existing  in  the  ignition  or  carburetion 
groups  are  usually  denoted  by  imperfect  operation  of 
the  motor,  such  as  lost  power,  and  misfiring,  derange- 
ments of  the  lubrication  or  cooling  systems  are  usually 
evident  by  overheating,  diminution  in  engine  capacity,  or 
noisy  operation.  Overheating  may  be  caused  by  poor 
carburetion  as  much  as  by  deficient  cooling  or  insufficient 
oiling.  When  the  oiling  group  is  not  functioning  as  it 
should  the  friction  between  the  motor  parts  produces  heat. 
If  the  cooling  system  is  in  proper  condition,  as  will  be 
evidenced  by  the  condition  of  the  water  in  the  radiator, 
and  the  carburetion  group  appears  to  be  in  good  condi- 
tion, the  overheating  is  probably  caused  by  some  defect 
in  the  oiling  system. 

The   conditions   that   most   commonly   result    in   poor 


358  Aviation  Engines 

lubrication  are:  Insufficient  oil  in  the  engine  crank-case 
or  sump,  broken  or  clogged  oil  pipes,  screen  at  filter  filled 
with  lint  or  dirt,  broken  oil  pump,  or  defective  oil-pump 
drive.  The  supply  of  oil  may  be  reduced  by  a  defective 
inlet  or  discharge-check  valve  at  the  mechanical  oiler  or 
worn  pumps.  A  clogged  oil  passage  or  pipe  leading  to 
an  important  bearing  point  will  cause  trouble  because 
the  oil  cannot  get  between  the  working  surfaces.  It  is 
well  to  remember  that  much  of  the  trouble  caused  by 
defective  oiling  may  be  prevented  by  using  only  the  best 
grades  of  lubricant,  and  even  if  all  parts  of  the  oil  sys- 
tem are  working  properly,  oils  of  poor  quality  will  cause 
friction  and  overheating. 


DEFECTS   IN    COOLING   SYSTEMS   OUTLINED 

Cooling  systems  are  very  simple  and  are  not  liable  to 
give  trouble  as  a  rule  if  the  radiator  is  kept  full  of  clean 
water  and  the  circulation  is  not  impeded.  When  over- 
heating is  due  to  defective  cooling  the  most  common 
troubles  are  those  that  impede  water  circulation.  If  the 
radiator  is  clogged  or  the  piping  of  water  jackets  filled 
with  rust  or  sediment  the  speed  of  water  circulation  will 
be  slow,  which  will  also  be  the  case  if  the  water  pump  or 
its  driving  means  fail.  Any  scale  or  sediment  in  the  water 
jackets  or  in  the  piping  or  radiator  passages  will  reduce 
the  heat  conductivity  of  the  metal  exposed  to  the  air,  and 
the  water  will  not  be  cooled  as  quickly  as  though  the  scale 
was  not  present. 

TJie  rubber  hose  often  used  in  making  the  flexible 
connections  demanded  between  the  radiator  and  water 
manifolds  of  the  engine  may  deteriorate  inside  and  par- 
ticles of  rubber  hang  down  that  will  reduce  the  area  of 
the  passage.  The  grease  from  the  grease  cups  mounted 
on  the  pump- shaft  bearing  to  lubricate  that  member  often 
finds  its  way  into  the  waiter  system  and  rots  the  inner 
walls  of  the  rubber  hose,  this  resulting  in  strips  of  the 
partly  decomposed  rubber  lining  hanging  down  and  re- 


Cooling  System  Faults  359 

striding  the  passage.  The  cooling  system  is  prone  to 
overheat  after  antifreezing  solutions  of  which  calcium 
chloride  forms  a  part  have  been  used.  This  is  due  to 
the  formation  of  crystals  of  salt  in  the  radiator  passages 
or  water  jackets,  and  these  crystals  can  only  be  dissolved 
by  suitable  chemical  means,  or  removed  by  scraping  when 
the  construction  permits. 

Overheating  is  often  caused  by  some  condition  in  the 
fuel  system  that  produces  too  rich  or  too  lean  mixture. 
Excess  gasoline  may  be  supplied  if  any  of  the  following 
conditions  are  present:  Bore  of  spray  nozzle  or  stand- 
pipe  too  large,  auxiliary  air- valve  spring  too  tight,  gaso- 
line level  too  high,  loose  regulating  valve,  fuel-soaked 
cork  float,  punctured  sheet-metal  float,  dirt  under  float 
control  shut-off  valve  or  insufficient  air  supply  because 
of  a  clogged  air  screen.  If  pressure  feed  is  utilized  there 
may  be  too  much  pressure  in  the  tank,  or  the  float  con- 
trolled mechanism  operating  the  shut-off  in  the  float  bowl 
of  the  carburetor  may  not  act  quickly  enough. 

SOME    CAUSES   OF   NOISY   OPEKATION 

There  are  a  number  of  power-plant  derangements 
which  give  positive  indication  because  of  noisy  operation. 
Any  knocking  or  rattling  sounds  are  usually  produced  by 
wear  in  connecting  rods  or  main  bearings  of  the  engine, 
though  sometimes  a  sharp  metallic  knock,  which  is  very 
much  the  same  as  that  produced  by  a  loose  bearing,  is  due 
to  carbon  deposits  in  the  cylinder  heads,  or  premature 
ignition  due  to  advanced  spark-time  lever.  Squeaking 
sounds  invariably  indicate  dry  bearings,  and  whenever 
such  a  sound  is  heard  it  should  be  immediately  located 
and  oil  applied  to  the  parts  thus  denoting  their  dry  con- 
dition. Whistling  or  blowing  sounds  are  produced  by 
leaks,  either  in  the  engine  itself  or  in  the  gas  manifolds. 
A  sharp  whistle  denotes  the  escape  of  gas  under  pressure 
and  is  usually  caused  by  a  defective  packing  or  gasket 
that  seals  a  portion  of  the  combustion  chamber  or  that  is 


360  Aviation  Engines 

used  for  a  joint  as  the  exhaust  manifold.  A  blowing 
sound  indicates  a  leaky  packing  in  crank-case.  Grinding 
noises  in  the  motor  are  usually  caused  by  the  timing  gears 
and  will  obtain  if  these  gears  are  dry  or  if  they  have  be- 
come worn.  Whenever  a  loud  knocking  sound  is  heard 
careful  inspection  should  be  made  to  locate  the  cause  of 
the  trouble.  Much  harm  may  be  done  in  a  few  minutes 
if  the  engine  is  run  with  loose  connecting  rod  or  bearings 
that  would  be  prevented  by  taking  up  the  wear  or  loose- 
ness between  the  parts  by  some  means  of  adjustment. 


BRIEF   SUMMARY   OF   HINTS   FOR   STARTING   ENGINE 

First  make  sure  that  all  cylinders  have  compression. 
To  ascertain  this,  open  pet  cocks  of  all  cylinders  except 
the  one  to  be  tested,  crank  over  motor  and  see  that  a 
strong  opposition  to  cranking  is  met  with  once  in  twro 
revolutions.  If  motor  has  no  pet  cocks,  crank  and  notice 
that  oppositions  are  met  at  equal  distances,  two  to  every 
revolution  of  the  starting  crank  in  a  four-cylinder  motor. 
If  compression  is  lacking,  examine  the  parts  of  the  cylin- 
der or  cylinders  at  fault  in  the  following  order,  trying  to 
start  the  motor  whenever  any  one  fault  is  found  and 
remedied.  See  that  the  valve  push  rods  or  rocker  arms 
do  not  touch  valve  stems  for  more  than  approximately 
y2  revolution  in  every  2  revolutions,  and  that  there  is  not 
more  than  .010  to  .020  inch  clearance  between  them  de- 
pending on  the  make  of  the  motor.  Make  sure  that  the 
exhaust  valve  seats.  To  determine  this  examine  the 
spring  and  see  that  it  is  connected  to  the  valve  stem 
properly.  Take  out  valve  and  see  that  there  is  no  ob- 
struction, such  as  carbon,  on  its  seat.  See  that  valve 
works  freely  in  its  guide.  Examine  inlet  valve  in  same 
manner.  Listen  for  hissing  sound  while  cranking  motor 
for  leaks  at  other  places. 

Make  sure  that  a  spark  occurs  in  each  cylinder  as 
follows:  If  magneto  or  magneto  and  battery  with  non- 
vibrating  coil  is  used:  Disconnect  wire  from  spark-plug, 


Summary  of  Hints  for  Starting  Engine        361 

hold  end  about  %  inch  from  cylinder  or  terminal  of  spark- 
plug. Have  motor  cranked  briskly  and  see  if  spark  oc- 
curs. Examine  adjustment  of  interrupter  points.  See  that 
wires  are  placed  correctly  and  not  short  circuited.  Take 
out  spark-plug  and  lay  it  on  the  cylinder,  being  careful 
that  base  of  plug  only  touches  the  cylinder  and  that  igni- 
tion wire  is  connected.  Have  motor  cranked  briskly  and 
see  if  spark  occurs.  Check  timing  of  magneto  and  see 
that  all  brushes  are  making  contact. 

See  if  there  is  gasoline  in  the  carburetor.  See  that 
there  is  gasoline  in  the  tank.  Examine  valve  at  tank. 
Prime  carburetor  and  see  that  spray  nozzle  passage  is 
clear.  Be  sure  throttle  is  open.  Prime  cylinders  by  put- 
ting about  a  teaspoonful  of  gasoline  in  through  pet  cock 
or  spark-plug  opening.  Adjust  carburetor  if  necessary. 

LOCATION    OF    ENGINE   TROUBLES    MADE    EASY 

The  following  tabulation  has  been  prepared  and  origi- 
nated by  the  writer  to  outline  in  a  simple  manner  the 
various  troubles  and  derangements  that  interfere  with 
efficient  internal-combustion  engine  action.  The  parts 
and  their  functions  are  practically  the  same  in  all  gas  or 
gasoline  engines  of  the  four-cycle  type,  and  the  general 
instructions  given  apply  just  as  well  to  all  hydro-carbon 
engines,  even  if  the  parts  differ  in  form  materially.  The 
essential  components  are  clearly  indicated  in  the  many 
part  sectional  drawings  in  this  book  so  they  may  be 
easily  recognized.  The  various  defects  that  may  mate- 
rialize are  tabulated  in  a  manner  that  makes  for  ready 
reference,  and  the  various  defective  conditions  are  found 
opposite  the  part  affected,  and  under  a  heading  that  de- 
notes the  main  trouble  to  which  the  others  are  con- 
tributing causes.  The  various  symptoms  denoting  the 
individual  troubles  outlined  are  given  to  facilitate  their 
recognition  in  a  positive  manner. 

Brief  note  is  also  made  of  the  remedies  for  the  restora- 
tion of  the  defective  part  or  condition.  It  is  apparent 


362  Aviation  Engines 

that  a  table  of  this  character  is  intended  merely  as  a 
guide,  and  it  is  a  compilation  of  practically  all  the  known 
troubles  that  may  materialize  in  gas-engine  operation. 
While  most  of  the  defects  outlined  are  common  enough 
to  warrant  suspicion,  they  will  never  exist  in  an  engine 
all  at  the  same  time,  and  it  will  be  necessary  to  make  a 
systematic  search  for  such  of  those  as  exist. 

To  use  the  list  advantageously,  it  is  necessary  to  know 
one  main  trouble  easily  recognized.  For  example,  if  the 
power  plant  is  noisy,  look  for  the  possible  troubles  under 
the  head  of  Noisy  Operation;  if  it  lacks  capacity,  the 
derangement  will  undoubtedly  be  found  under  the  head  of 
Lost  Power.  It  is  assumed  in  all  cases  that  the  trouble 
exists  in  the  power  plant  or  its  components,  and  not  in 
the  auxiliary  members  of  the  ignition,  carburetion,  lubri- 
cation, or  cooling  systems.  The  novice  and  student  will 
readily  recognize  the  parts  of  the  average  aviation  engine 
by  referring  to  the  very  complete  and  clearly  lettered 
illustrations  of  mechanism  given  in  many  parts  of  this 
treatise. 


Power  and  Overheating 


363 


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Ignition  System  Troubles  369 

IGNITION  SYSTEM  TROUBLES  ONLY 
Motor  Will  Not  Start  or  Starts  Hard 

Loose  Battery  Terminal. 

Magneto  Ground  Wire  Shorted. 

Magneto  Defective  (No  Spark  at  Plugs). 

Broken  Spark  Plug  Insulation. 

Carbon  Deposits  or  Oil  Between  Plug  Points. 

Spark-Plug  Points  Too  Near  Together  or  Far  Apart. 

Wrong  Cables  to  Plugs. 

Short  Circuited  Secondary  Cable. 

Broken  Secondary  Cable. 


Dry  Battery  Weak. 
Storage  Battery  Discharged. 
Poor  Contact  at  Timer. 
Timer  Points  Dirty. 


Battery  Systems 
Only.  ' 


Poor  Contact  at  Switch. 

Primary  Wires  Broken,  or  Short  Circuited.   -~ 

Battery  Grounded  in  Metal  Container. 

T3  j          n  -D     i  T  ^011  Ignition 

Battery  Connectors  Broken  or  Loose.  ~     t       n  1 

Timer  Points  Out  of  Adjustment. 
Defects  in  Induction  Coil. 

Ignition  Timing  Wrong,  Spark  Too  Late  or  Too  Early. 

Defective  Platinum  Points  in  Breaker  Box  (Magneto). 

Points  Not  Separating. 

Broken  Contact  Maker  Spring. 

No  Contact  at  Secondary  Collector  Brush. 

Platinum  Contact  Points  Burnt  or  Pitted. 

Contact  Breaker  Bell  Crank  Stuck. 

Fiber  Bushing  in  Bell  Crank  Swollen. 

Short  Circuiting  Spring  Always  in  Contact. 

Dirt  or  Water  in  Magneto  Casing. 

Oil  in  Contact  Breaker. 

Oil  Soaked  Brush  and  Collector  Ring. 

Distributor  Filled  with  Carbon  Particles. 


370  Aviation  Engines 

Motor  Stops  Without  Warning 

Broken  Magneto  Carbon  Brush. 

Broken  Lead  Wire. 

Broken  Ground  Wire. 

Battery  Ignition  Systems. 

Water  on  High  Tension  Magneto  Terminal. 

Main  Secondary  Cable  Burnt  Through  by  Hot  Exhaust 
Pipe  (Transformer  Coil,  Magneto  Systems). 

Particle  of  Carbon  Between  Spark  Plug  Points. 

Magneto  Short  Circuited  by  Ground  Wire. 

Magneto  Out  of  Time,  Due  to  Slipping  Drive. 

Water  or  Oil  in  Safety  Spark  Gap  (Multi-cylinder  Mag- 
neto). 

Magneto  Contact  Breaker  or  Timer  Stuck  in  Eetard 
Position. 

Worn  Fiber  Block  in  Magneto  Contact  Breaker. 

Binding  Fiber  Bushing  in  Contact  Breaker  Bell  Crank. 

Spark  Advance  Eod  or  Wire  Broken. 

Contact  Breaker  Parts  Stuck. 

Motor  Runs  Irregularly  or  Misfires 

Loose  Wiring  or  Terminals. 

Broken  Spark-Plug  Insulator. 

Spark-Plug  Points  Sooted  or  Oily. 

Wrong  Spark  Gap  at  Plug  Points. 

Leaking  Secondary  Cable. 

Prematurely  Grounded  Primary  Wire. 

Batteries  Running  Down  (Battery  Ignition  only). 

Poor  Adjustment  of  Contact  Points  at  Timer. 

Wire  Broken  Inside  of  Insulation. 

Loose  Platinum  Points  in  Magneto. 

Weak  Contact  Spring. 

Broken  Collector  Brush. 

Dirt  in  Magneto  Distributor  Casing  or  Contact  Breaker. 

Worn  Fiber  Block  or  Cam  Plate  in  Magneto. 


Ignition  System  Troubles 


371 


"Worn  Cam  or  Contact  Eoll  in  Timer    (Battery  System 

only). 

Dirty  Oil  in  Timer. 
Sticking  Coil  Vibrators. 
Coil  Vibrator  Points  Pitted. 
Oil  Soaked  Magneto  Winding. 
Punctured  Magneto  or  Coil  Winding. 
Distributor  Contact  Segments  Bough. 
Sulphated  Storage  Battery  Terminals. 
Weak  Magnets  in  Magneto. 
Poor  Contact  at  Magneto  Contact  Breaker  Points. 


DEFECTS   IN   ELECTRICAL   SYSTEM    COMPONENTS 

To  further  simplify  the  location  of  electrical  system 
faults  it  is  thought  desirable  to  outline  the  defects  that 
can  be  present  in  the  various  parts  of  the  individual  de- 
vices comprising  the  ignition  system.  If  an  airplane 
engine  is  provided  with  magneto  ignition  solely,  as  most 
engines  are  at  the  present  time,  no  attention  need  be 
paid  to  such  items  as  storage  or  dry  batteries,  timer  or 
induction  coil.  There  seems  to  be  some  development  in 
the  direction  of  battery  ignition  so  it  has  been  considered 
desirable  to  include  components  of  these  systems  as  well 
as  the  almost  universally  used  magneto  group. .  Spark- 
plugs, wiring  and  switches  are  needed  with  either  system. 


DEFECT 

Insulation  cracked. 
Insulation  oil  soaked. 
Carbon  deposits. 
Insulator  loose. 
Gasket  broken. 
Electrode  loose  on  shell. 
Wire  loose  in  insulator. 
Air  gap  too  close. 
Air  gap  too  wide. 

Loose  terminal. 

Plug  loose  in  cylinder. 

Mica  insulation  oil  soaked. 


SPARK-PLUGS 

TBOTJBLE   CAUSED 

Plug  inoperative. 
Cylinder  misfires. 
Short  circuited  spark. 
Cylinder  misfires. 
Gas  leaks  by. 
Cylinder  misfires. 
Cylinder  misfires. 
Short  circuits  spark. 
Spark  will  not  jump. 

Cylinder  may  misfire. 
.  Gas  leaks. 
Short  circuits  spark. 


EEMEDY 

New  insulation. 

Clean. 

Remove. 

Tighten. 

New  gasket. 

Tighten. 

Tighten. 

Set  correctly. 

Set  points  l/32'< 

apart. 
Tighten. 
Tighten. 
Replace. 


372 


Aviation  Engines 


MAGNETO 


DEFECT 

Dirty  oil  in  distributor. 
Metal  dust  in  distributor. 
Brushes  not  making  contact. 
Distributor  segments  worn. 

Collecting  brush  broken. 

Distributing  brush  broken. 

Oil  soaked  winding. 

Magnets  loose  on  pole  pieces. 

Armature  rubs. 

Bearings  worn. 

Magnets  weak. 

Contact  breaker  points  pitted. 

Breaker   points  out   of   adjust- 
ment 

Defective  winding  (rare). 

Punctured  condenser  (rare). 

Driving  gear  loose. 

Magneto  armature  out  of  time. 

Magneto  loose  on  base. 

Contact  breaker  cam  worn. 

Fibre  shoe  or  rolls  worn 
(Bosch). 

Fibre  bushing  binding  in  con- 
tact lever   ( Bosch ) . 

Contact  lever  return  spring 
broken. 

Contact  lever  return  spring 
weak. 

Ground  wire  grounded. 

Ground  wire  broken. 

Safety  spark  gap  dirty. 

Fused  metal  in  spark  gap. 

Safety  spark  gap  points  too 
close. 

Loose  distributor  terminals. 

Contact  breaker  sticks. 


TROUBLE    CAUSED 

Engine  misfires. 
Engine  misfires. 
Current  cannot  pass. 
Engine  misfires. 

Engine  misfires. 
Engine  misfires. 
Engine  misfires. 
Engine  misfires. 
Engine  misfires. 
Noisy. 

Weak  spark. 
Engine  misfires. 
Engine  misfires. 

No  spark. 

Weak  or  no  spark. 

Noise. 

Spark  will  not  fire  charge. 

Misfiring  and  noisy. 

Misfiring. 

Misfiring. 

Misfiring. 
No  spark. 
Misfiring. 

No  spark. 

Engine  will  not  stop. 

.No  spark. 

No  spark. 

Misfiring. 

Misfiring. 

No  spark  control. 


Magneto  switch  short-circuited.    No  spark. 
Magneto  switch  open  circuit.        No  engine  stop. 


REMEDY 

Clean. 
Clean. 

Strengthen  spring. 
Secure  even  bear- 
ing. 

New  brush. 
New  brush. 
Clean. 

Tighten  screws. 
Repair  bearings. 
Replace. 
Recharge. 
Clean. 
Reset. 

Replace. 
Replace. 
Tighten. 
Retime. 
Tighten. 
Replace. 
Replace. 

Ream  slightly. 

Replace. 

Replace. 

Insulate. 
Connect  up. 
Clean. 
Remove. 
Set  properly. 

Tighten. 

Remove  and  clean 

bearings. 
Insulate. 
Restore  contact. 


STORAGE    BATTERY 


DEFECT 

Electrolyte  low. 

Loose  terminals. 
Sulphated  terminals. 


Battery  discharged. 
Electrolyte  weak. 

Plates  sulphated. 
Sediment  or  mud  in  bottom. 
Active  material  loose  in  grids. 


TROUBLE    CAUSED 

Weak  current. 

Misfiring. 
Misfiring. 


Misfiring  or  no  spark. 
Weak  current. 

Poor  capacity. 
Weak  current. 
Poor  capacity. 


REMEDY 

Replenish  with  dis- 
tilled water. 

Tighten. 

Clean  thoroughly 
and  coat  with 
vaseline. 

New  charge. 

Bring  to  proper 
specific  gravity. 

Special  slow  charge. 

Clean  out. 

New  plates. 


Ignition  System  Troubles 

STORAGE    BATTERY— Continued 


373 


DEFECT 


Moisture  or  acid  on  top  of 

cells. 

Plugged  vent  cap. 
Cracked  vent  cap. 
Cracked  cell  jar. 


TROUBLE    CAUSED 

Shorts  terminals. 

Buckles  cell  jars. 
Acid  spills  out. 
Electrolyte  runs  out. 


REMEDY 

Remove. 

Make  vent  hole. 
New  cap. 
New  jar. 


DRY    CELL    BATTERY 


DETECT 


Broken  wires. 

Loose  terminals. 

Weak  cell   (7  amperes  or  less) 

Cells  in  contact. 

Water  in  battery  box. 


TROUBLE    CAUSED 

No  current. 
Misfiring. 
Misfiring. 
Short  circuit. 

Short  circuit. 


REMEDY 

New  wires. 
Tighten. 
New  cells. 
Separate  and  insu- 
late. 
Dry  out. 


DEFECT 

Contact  segments  worn  or 

pitted. 
Platinum  points  pitted. 

Dirty  oil  or  metal  dust  in 

interior. 
Worn  bearing. 
Loose  terminals. 
Worn  revolving  contact  brush. 
Out  of  time. 


TIMER 

TROUBLE   CAUSED 

Misfiring. 


REMEDY 

Grind  down  smooth. 


Misfiring. 
Misfiring. 

Smooth  with  oil 
stone. 
Clean  out. 

Misfiring. 
Misfiring. 
Misfiring. 
Irregular  spark. 

Replace. 
.     Tighten. 
Replace. 
Reset. 

DEFECT 

Loose  terminals. 
Broken  connections. 
Vibrators  out  of  adjustment. 
Vibrator  points  pitted. 
Defective  condenser  ") 
Defective  winding     } 
Poor  contact  at  switch. 
Broken  internal  wiring. 
Poor  coil  unit. 


INDUCTION   COIL 

TROUBLE    CAUSED 

Misfiring. 
No  spark. 
Misfiring. 
Misfiring. 

No  spark. 

Misfiring. 
No  spark. 
One  cylinder  affected. 


REMEDY 

Tighten. 

Make  new  joints. 

Readjust. 

Clean. 

Send  to  maker  for 

repairs. 
Tighten. 
Replace. 
Replace. 


DEFECT 

Loose  terminals  anywhere. 
Broken  plug  wire. 
Broken  timer  wire. 
Broken  main  battery  wire. 
Broken  battery  ground  wire, 
Broken  magneto  ground  wire. 
Chafed  insulation  anywhere.    ") 
Short  circuit  anywhere.  j 


WIRING 

TROUBLE   CAUSED  REMEDY 

Misfiring.  Tighten. 

One  cylinder  will  not  fire.  Replace. 

One  coil  will  not  buzz.  Replace. 

No  spark.  Replace. 

Engine  will  not  stop.  Replace. 

Misfiring.  Insulate. 


374  Aviation  Engines 

CARBURETTOR  SYSTEM  FAULTS  SUMMARIZED 

Motor  Starts  Hard  or  Will  Not  Start 
No  Gasoline  in  Tank. 

No  Gasoline  in  Carburetor  Float  Chamber. 
Tank  Shut-Off  Closed. 
Clogged  Filter  Screen. 
Fuel  Supply  Pipe  Clogged. 
Gasoline  Level  Too  Low. 
Gasoline  Level  Too  High  (Flooding). 
Bent  or  Stuck  Float  Lever. 
Loose  or  Defective  Inlet  Manifold. 
Not  Enough  Gasoline  at  Jet. 
Cylinders  Flooded  with  Gas. 
Fuel  Soaked  Cork  Float  (Causes  Flooding ). 
Water  in  Carburetor  Spray  Nozzle. 
Dirt  in  Float  Chamber. 
Gas  Mixture  Too  Lean. 
Carburetor  Frozen  (Winter  Only). 

•  Motor  Stops  In  Flight 

Gasoline  Shut-Off  Valve  Jarred  Closed. 

Gasoline  Supply  Pipe  Clogged. 

No  Gasoline  in  Tank. 

Spray  Nozzle  Stopped  Up. 

Water  in  Spray  Nozzle. 

Particles  of  Carbon  Between  Spark-Plug  Points. 

Magneto  Short  Circuited  by  Ground  in  Wire. 

Air  Lock  in  Gasoline  Pipe. 

Broken  Air  Line  or  Leaky  Tank  (Pressure  Feed  System 

Only). 

Fuel  Supply  Pipe  Partially  Clogged. 
Air  Vent  in  Tank  Filler  Cap  Stopped  Up  (Gravity  and 

Vacuum  Feed  System). 
Float  Needle  Valve  Stuck. 
Water  or  Dirt  in  Spray  Nozzle. 
Mixture  Adjusting  Needle  Jarred  Loose  (Eotary  Motors 

Only). 


Carburetion  System  Faults  375 

Motor  Races,  Will  Not,  Throttle  Down 

Air  Leak  in  Inlet  Piping. 

Air  Leak  Through  Inlet  Valve  Guides. 

Control  Eods  Broken. 

Defective  Induction  Pipe  Joints. 

Leaky  Carburetor  Flange  Packing. 

Throttle  Not  Closing. 

Poor  Slow  Speed  Adjustment  (Zenith  Carburetor). 

Motor  Misfires 

Carburetor  Float  Chamber  Getting  Dry. 

Water  or  Dirt  in  Gasoline. 

Poor  Gasoline  Adjustment  (Eotary  Motors). 

Not  Enough  Gasoline  in  Float  Chamber. 

Too  Much  Gasoline,  Carburetor  Flooding. 

Incorrect  Jet  or  Choke  (Zenith  Carburetor). 

Broken  Cylinder  Head  Packing  Between  Cylinders. 

Noisy  Operation 

Popping  or  Blowing  Back  in  Carburetor. 

Incorrectly  Timed  Inlet  Valves. 

Inlet  Valve  Not  Seating. 

Defective  Inlet  Valve  Spring. 

Dirt  Under  Inlet  Valve  Seat. 

Not  Enough  Gasoline  (Open  Needle  Valve). 

Muffler  or  Manifold  Explosions. 

Mixture  Not  Exploding  Regularly. 

Exhaust  Valve  Sticking. 

Dirt  Under  Exhaust  Valve  Seat. 


CHAPTEE   XI 

Tools  for  Adjusting  and  Erecting — Forms  of  Wrenches — Use  and  Care 
of  Files — Split  Pin  Removal  and  Installation — Complete  Chisel 
Set — Drilling  Machines — Drills,  Reamers,  Taps  and  Dies — Meas- 
uring Tools — Micrometer  Calipers  and  Their  Use — Typical  Tool 
Outfits — Special  Hall-Scott  Tools — Overhauling  Airplane  Engines 
— Taking  Engine  Down — Defects  in  Cylinders — Carbon  Deposits, 
Cause  and  Prevention — Use  of  Carbon  Scrapers — Burning  Out 
Carbon  with  Oxygen — Repairing  Scored  Cylinders — Valve  Re- 
moval and  Inspection — Reseating  and  Truing  Valves — Valve 
Grinding  Processes — Depreciation  in  Valve  Operating  System — 
Piston  Troubles — Piston  Ring  Manipulation — Fitting  Piston  Rings 
— Wrist-Pin  Wear — Inspection  and  Refitting;  of  Engine  Bearings 
— Scraping  Brasses  to  Fit — Fitting  Connecting  Rods — Testing  for 
Bearing  Parallelism — Cam-Shafts  and  Timing  Gears — Precautions 
in  Reassembling  Parts. 

TOOLS   FOR   ADJUSTING  AND   ERECTING 

A  very  complete  outfit  of  small  tools,  some  of  which 
are  furnished  as  part  of  the  tool  equipment  of  various 
engines  are  shown  in  group  at  Fig.  163.  This  group  in- 
cludes all  of  the  tools  necessary  to  complete  a  very  prac- 
tical kit  and  it  is  not  unusual  for  the  mechanic  who  is 
continually  dismantling  and  erecting  engines  to  possess 
even  a  larger  assortment  than  indicated.  The  small  bench 
vise  provided  is  a  useful  auxiliary  that  can  be  clamped 
to  any  convenient  bench  or  table  or  even  fuselage  longeron 
in  an  emergency  and  should  have  jaws  at  least  three 
inches  wide  and  capable  of  opening  four  or  five  inches. 
It  is  especially  useful  in  that  it  will  save  trips  to  the 
bench  vises,  as  it  has  adequate  capacity  to  handle  practi- 
cally any  of  the  small  parts  that  need  to  be  worked  on 
when  making  repairs.  A  blow  torch,  tinner's  snips  and 
soldering  copper  are  very  useful  in  sheet  metal  work  and 
in  making  any  repairs  requiring  the  use  of  solder.  The 
torch  can  be  used  in  any  operation  requiring  a  source  of 

376 


00 

:*r    ~          Small 

Tinners 

_^      Snips 
Oil  Can 


Screw  Drivers 
(AH  Me+al  Type) 


Vise 


Machinists  Hammer 

SESJD (^^ 

Soldering  Copper 


c  SideCuttinq       Combination 

Socket  Wrench  Set    Parallel  Jaw  Plie 


Adjustable  End  Wrench 
Bicycle  Wrench 


Spark  Plug 
Small  Socket  Wrench       Socket 


Adjustable  End  Wrench 
Spanner 


Thin  Wrench 
Bearing  Scraper 


'Combination Pliers    Cutting 
Pliers 


Cold  Chisel 


Center  Punch 


Carbon  Scrapers 


End  Wrenches 


Double  End  Wrenches 


Fig.    163. — Practical   Hand   Tools   Useful   in   Dismantling   and   Repairing 

Airplane  Engines. 


377 


378  Aviation  Engines 

heat.  The  large  box  wrench  shown  under  the  vise  is  used 
for  removing  large  special-  nuts  and  sometimes  has  one 
end  of  the  proper  size  to  fit  the  valve  chamber  cap.  The 
piston  ring  removers  are  easily  made  from  thin  strips  of 
sheet  metal  securely  brazed  or  soldered  to  a  light  wire 
handle.  These  are  used  in  sets  of  three  for  removing 
and  applying  piston  rings  in  a  manner  to  be  indicated. 
The  uses  of  the  wrenches,  screw  drivers,  and  pliers  shown 
are  known  to  all  and  the  variety  outlined  should  be  suffi- 
cient for  all  ordinary  work  of  restoration.  The  wrench 
equipment  is  very  complete,  including  a  set  of  open  end 
S-wrenches  to  fit  all  standard  bolts,  a  spanner  wrench, 
socket  or  box  wrenches  for  bolts  that  are  inaccessible  with 
the  ordinary  type,  adjustable  end  wrenches,  a  thin  monkey 
wrench  of  medium  size,  a  bicycle  wrench  for  handling 
small  nuts  and  bolts,  a  Stillson  wrench  for  pipe  and  a 
large  adjustable  monkey  wrench  for  the  stubborn  fasten- 
ings of  large  size. 

Four  different  types  of  pliers  are  shown,  one  being  a 
parallel  jaw  type  with  size  cutting  attachment,  while  the 
other  illustrated  near  it  is  a  combination  parallel  jaw  type 
adapted  for  use  on  round  work  as  well  as  in  handling 
flat  stock.  The  most  popular  form  of  pliers  is  the  com- 
bination pattern  shown  beneath  the  socket  wrench  set. 
This  is  made  of  substantial  drop  forgings  having  a  hinged 
joint  that  can  be  set  so  that  a  very  wide  opening  at  the 
jaws  is  possible.  These  can  be  used  on  round  work  and 
for  wire  cutting  as  well  as  for  handling  flat  work.  Eound 
nose  pliers  are  very  useful  also. 

A  very  complete  set  of  files,  including  square,  half 
round,  mill,  flat  bastard,  three-cornered  and  rat  tail  are 
also  necessary.  A  hacksaw-  frame  and  a  number  of  saws, 
some  with  fine  teeth  for  tubing  and  others  with  coarser 
teeth  for  bar  or  solid  stock  will  be  found  almost  indis- 
pensable. A  complete  punch  and  chisel  set  should  be  pro- 
vided, samples  of  which  are  shown  in  the  group  while  the 
complete  outfit  is  outlined  in  another  illustration.  A 
number  of  different  forms  and  sizes  of  chisels  are  neces- 


Forms  of  Wrenches  379 

sary,  as  one  type  is  not  suitable  for  all  classes  -of  work. 
The  adjustable  end  wrenches  can  be  used  in  many  places 
where  a  monkey  wrench  cannot  be  fitted  and  where  it 
will  be  difficult  to  use  a  wrench  having  a  fixed  opening. 
The  Stillson  pipe  wrench  is  useful  in  turning  studs,  round 
rods,  and  pipes  that  cannot  be  turned  by  any  other  means. 
A  complete  shop  kit  must  necessarily  include  various  sizes 
for  Stillson  and  monkey  wrenches,  as  no  one  size  can  be 
expected  to  handle  the  wide  range  of  work  the  engine 
repairman  must  cope  with.  Three  sizes  of  each  form  of 
wrench  can  be  used,  one,  a  6  inch,  is  as  small  as  is  needed 
while  a  12  inch  tool  will  handle  almost  any  piece  of  pipe 
or  nut  used  in  engine  construction. 

Three  or  four  sizes  of  hammers  should  be  provided, 
according  to  individual  requirement,  these  being  small 
riveting,  medium  and  heavyweight  machinist's  hammers. 
A  very  practical  tool  of  this  nature  for  the  repair  shop 
can  be  used  as  a  hammer,  screw  driver  or  pry  iron.  It  is 
known  as  the  " Spartan"  hammer  and  is  a  tool  steel  drop 
forging  in  one  piece  having  the  working  surfaces  properly 
hardened  and  tempered  while  the  metal  is  distributed  so 
as  to  give  a  good  balance  to  the  head  and  a  comfortable 
grip  to  the  handle.  The  hammer  head  provides  a  posi- 
tive and  comfortable  T-handle  when  the  tool  is  used  as 
a  screw  driver  or  " tommy"  bar.  Machinist's  hammers 
are  provided  with  three  types  of  heads,  these  being  of 
various  weights.  The  form  most  commonly  used  is 
termed  the  "ball  pein"  on  account  of  the  shape  of  the 
portion  used  for  riveting.  The  straight  pein  is  just  the 
same  as  the  cross  pein,  except  that  in  the  latter  the 
straight  portion  is  at  right  angles  to  the  hammer  handle, 
while  in  the  former  it  is  parallel  to  that  member. 

FORMS   OF   WRENCHES 

Wrenches  have  been  made  in  infinite  variety  and  there 
are  a  score  or  more  patterns  of  different  types  of  ad- 
justable socket  and  off-set  wrenches.  The  various  wrench 


380 


Aviation  Engines 


types  that  differ  from  the  more  conventional  monkey 
wrenches  or  those  of  the  Stillson  pattern  are  shown  at 
Fig.  164.  The  " perfect  handle"  is  a  drop  forged  open 
end  form  provided  with  a  wooden  handle  similar  to  that 
used  on  a  monkey  wrench  in  order  to  provide  a  better 
grip  for  the  hand.  The  " Saxon"  wrench  is  a  double 
alligator  form,  so  called  because  the  jaws  are  in  the  form 
of  a  V-groove  having  one  side  of  the  V  plain,  while  the 
other  is  serrated  in  order  to  secure  a  tight  grip  on  round 
objects.  In  the  form  shown,  two  jaws  of  varying  sizes 


5TARRETT 


MILLER 


Fig.  164. — Wrenches  are  Offered  in  Many  Forms. 

are  provided,  one  for  large  work,  the  other  to  handle  the 
smaller  rods.  One  of  the  novel  features  in  connection 
with  this  wrench  is  the  provision  of  a  triple  die  block  in 
the  centre  of  the  handle  which  is  provided  with  three 
most  commonly  used  of  the  standard  threads  including 
%6-inch-18,  %-inch-16,  and  %-inch-13.  This  is  useful  in 
cleaning  up  burred  threads  on  bolts  before  they  are 
replaced,  as  burring  is  unavoidable  if  it  has  been  neces- 
sary to  drive  them  out  with  a  hammer.  The  "Lakeside" 
wrench  has  an  adjustable  pawl  engaging  with  one  of  a 
series  of  notches  by  which  the  opening  may  be  held  in 
any  desired  position. 

Ever  since  the  socket  wrench  was  invented  it  has  been 


Forms  of  Wrenches  381 

a  popular  form  because  it  can  be  used  in  many  places 
where  the  ordinary  open  end  or  monkey  wrench  cannot 
be  applied  owing  to  lack  of  room  for  the  head  of  the 
wrench.  A  typical  set  which  has  been  made  to  fit  in  a  very 
small  space  is  shown  at  D.  It  consists  of  a  handle,  which 
is  nickel-plated  and  highly  polished,  a  long  extension  bar, 
a  universal  joint  and  a  number  of  case  hardened  cold 
drawn  steel  sockets  to  fit  all  commonly  used  standard  nuts 
and  bolt  heads.  Two  screw-driver  bits,  one  small  and  the 
other  large  to  fit  the  handle,  and  a  long  socket  to  fit  spark- 
plugs are  also  included  in  this  outfit.  The  universal  joint 
permits  one  to  remove  nuts  in  a  position  that  would  be 
inaccessible  to  any  other  form  of  wrench,  as  it  enables 
the  socket  to  be  turned  even  if  the  handle  is  at  one  side 
of  an  intervening  obstruction. 

The  "  Pick-up "  wrench,  shown  at  E,  is  used  for  spark- 
plugs and  the  upper  end  of  the  socket  is  provided  with  a 
series  of  grooves  into  which  a  suitable  blade  carried  by 
the  handle  can  be  dropped.  The  handle  is  pivoted  to  the 
top  of  the  socket  in  such  a  way  that  the  blades  may  be 
picked  up  out  of  the  grooves  by  lifting  on  the  end  of  the 
handle  and  dropped  in  again  when  the  handle  is  swung 
around  to  the  proper  point  to  get  another  hold  on  the 
socket.  The  "Miller"  wrench  shown  at  F,  is  a  combina- 
tion socket  and  open  end  type,  made  especially  for  use 
with  spark-plugs.  Both  the  open  end 'and  the  socket  are 
convenient.  The  "Handy"  set  shown  at  G,  consists  of  a 
number  of  thin  stamped  wrenches  of  steel  held  together 
in  a  group  by  a  simple  clamp  fitting,  which  enables  either 
end  of  any  one  of  the  four  double  wrenches  to  be  brought 
into  play  according  to  the  size  of  the  nut  to  be  turned. 
The  "Cronk"  wrench  shown  at  H,  is  a  simple  stamping 
having  an  alligator  opening  at  one  end  and  a  stepped 
opening  capable  of  handling  four  different  sizes  of  stand- 
ard nuts  or  bolt  heads  at  the  other.  Such  wrenches  are 
very  cheap  and  are  worth  many  times  their  small  cost, 
especially  for  fitting  nuts  where  there  is  not  sufficient 
room  to  admit  the  more  conventional  pattern.  The 


382  Aviation  Engines 

"Starrett"  wrench  set,  which  is  shown  at  I,  consists  of 
a  ratchet  handle  together  with  an  extension  bar  and  uni- 
versal joint,  a  spark-plug  socket,  a  drilling  attachment 
which  takes  standard  square  shank  drills  from  %-inch  to 
3/2-inch  in  diameter,  a  double  ended  screw-driver  bit  and 
several  adjustments  to  go  with  the  drilling  attachment. 
Twenty-eight  assorted  cold  drawn  steel  sockets  similar  in 
design  to  those  shown  at  D,  to  fit  all  standard  sizes  of 
square  and  hexagonal  headed  nuts  are  also  included.  The 
reversible  ratchet  handle,  which  may  be  slipped  over  the 
extension  bar  or  the  universal  joint  and  which  is  also 
adapted  to  take  the  squared  end  of  any  one  of  the  sockets 
is  exceptionally  useful  in  permitting,  as  it  does,  the  in- 
stant release  of  pressure  when  it  is  desired  to  swing  the 
handle  back  to  get  another  hold  on  the  nut.  The  socket 
wrench  sets  are  usually  supplied  in  hard  wood  cases  or 
in  leather  bags  so  that  they  may  be  kept  together  and 
protected  against  loss  or  damage.  With  a  properly  se- 
lected socket  wrench  set,  either  of  the  ratchet  handle  or 
T-handle  form,  any  nut  on  the  engine  may  be  reached  and 
end  wrenches  will  not  be  necessary. 


USE   AND    CARE    OF   FILES 

Mention  has  been  previously  made  of  the  importance 
of  providing  a  complete  set  of  files  and  suitable  handles. 
These  should  be  in  various  grades  or  degrees  of  fineness 
and  three  of  each  kind  should  be  provided.  In  the  flat 
and  half  round  files  three  grades  are  necessary,  one  with 
coarse  teeth  for  roughing,  and  others  with  medium  and 
fine  teeth  for  the  finishing  cuts.  The  round  or  rat  tail 
file  is  necessary  in  filing  out  small  holes,  the  half  round 
for  finishing  the  interior  of  large  ones.  Half  round  files 
are  also  well  adapted  for  finishing  surfaces  of  peculiar 
contour,  such  as  the  inside  of  bearing  boxes,  connecting 
rod  and  main  bearing  caps,  etc.  Square  files  are  useful 
in  finishing  keyways  or  cleaning  out  burred  splines,  while 
the  triangular  section  or  three-cornered  file  is  of  value  in 


Use  and  Care  of  Files 


383 


cleaning  out  burred  threads  and  sharp  corners.    Flat  files 
are  used  on  all  plane  surfaces. 

The  file  brush  shown  at  Fig.  165,  A,  consists  of  a  large 
number  of  wire  bristles  attached  to  a  substantial  wood 


Fig.  165. — Illustrating  Use  and  Care  of  Files. 

back  having  a  handle  of  convenient  form  so  that  the 
bristles  may  be  drawn  through  the  interstices  between 
the  teeth  of  the  file  to  remove  dirt  and  grease.  If  the 


384  Aviation  Engines 

teeth  are  filled  with  pieces  of  soft  metal,  such  as  solder 
or  babbitt,  it  may  be  necessary  to  remove  this  accumula- 
tion with  a  piece  of  sheet  metal  as  indicated  at  Fig. 
165,  B.  The  method  of  holding  a  file  for  working  on 
plain  surfaces  when  it  is  fitted  with  the  regular  form  of 
wooden  handle  is  shown  at  C,  while  two  types  of  handles 
enabling  the  mechanic  to  use  the  flat  file  on  plain  sur- 
faces of  such  size  that  the  handle  type  indicated  at  C, 
could  not  be  used  on  account  of  interfering  with  the  sur- 
face finished  are  shown  at  D.  The  method  of  using  a 
file  when  surfaces  are  finished  by  draw  filing  is  shown  at 
E.  This  differs  from  the  usual  method  of  filing  and  is 
only  used  when  surfaces  are  to  be  polished  and  very  little 
metal  removed. 


SPLIT   PIN   REMOVAL   AND   INSERTION 

One  of  the  most  widely  used  of  the  locking  means  to 
prevent  nuts  or  bolts  from  becoming  loose  is  the  simple 
split  pin,  sometimes  called  a  "cotter  pin."  These  can  be 
handled  very  easily  if  the  special  pliers  shown  at  Fig. 
166,  A,  are  used.  They  have  a  curved  jaw  that, permits 
of  grasping  the  pin  firmly  and  inserting  it  in  the  hole 
ready  to  receive  it.  It  is  not  easy  to  insert  these  split 
pins  by  other  means  because  the  ends  are  usually  spread 
out  and  it  is  hard  to  enter  the  pin  in  the  hole.  With  the 
cotter  pin  pliers  the  ends  may  be  brought  close  together 
and  as  the  plier  jaws  are  small  the  pin  may  be  easily 
pushed  in  place.  Another  use  of  this  plier,  also  indicated, 
is  to  bend  over  the  ends  of  the  split  pin  in  order  to  pre- 
vent it  from  fal-ling  out.  To  remove  these  pins  a  simple 
curved  lever,  as  shown  at  Fig.  166,  B,  is  used.  This  has 
one  end  tapering  to  a  point  and  is  intended  to  be  in- 
serted in  the  eye  of  the  cotter  pin,  the  purchase  offered 
by  the  handle  permitting  of  ready  removal  of  the  pin 
after  the  ends  have  been  closed  by  the  cotter  pin  pliers. 


Miscellaneous  Small  Tools 


385 


COMPLETE    CHISEL   SET 

A  complete  chisel  set  suitable  for  repair  shop  use  is 
also  shown  at  Fig.  166.  The  type  at  C  is  known  as  a 
"cape"-  chisel  and  has  a  narrow  cutting  point  and  is  in- 
tended to  chip  keyways,  remove  metal  out  of  corners  and 
for  all  other  work  where  the  broad  cutting  edge  chisel, 


Tig.  166. — Outlining  Use  of  Cotter  Pin  Pliers,  Spring  Winder,  and  Showing 
Practical  Outfit  of  Chisels. 

shown  at  D,  cannot  be  used.  The  form  with  the  wide 
cutting  edge  is  used  in  chipping,  cutting  sheet  metal,  etc. 
At  E,  a  round  nose  chisel  used  in  making  oil  ways  is  out- 
lined, while  a  similar  tool  having  a  pointed  cutting  edge 
and  often  used  for  the  same  purpose  is  shown  at  F.  The 
centre  punch  depicted  at  G,  is  very  useful  for  marking 
parts  either  for  identification  or  for  drilling.  In  addition 


386  Aviation  Engines 

to  the  chisels  shown,  a  number  of  solid  punches  or  drifts 
resembling  very  much  that  shown  at  E,  except  that  the 
point  is  blunt  should  be  provided  to  drive  out  taper  pins, 
bolts,  rivets,  and  other  fastenings  of  this  nature.  These 
should  be  provided  in  the  common  sizes.  A  complete  set 
of  real  value  would  start  at  %-inch  and  increase  by  incre- 
ments of  %2-inch  up  to  %-inch.  A  simple  spring  winder 
is  shown  at  Fig.  166,  H,  this  making  it  possible  for  the 
repairman  to  wind  coil  springs,  either  on  the  lathe  or  in 
the  vise.  It  will  handle  a  number  of  different  sizes  of 
wire  and  can  be  set  to  space  the  coils  as  desired. 


DRILLING   MACHINES 

Drilling  machines  may  be  of  two  kinds,  hand  or  power 
operated.  For  drilling  small  holes  in  metal  it  is  neces- 
sary to  run  the  drill  fast,  therefore  the  drill  chuck  is 
usually  driven  by  gearing  in  order  to  produce  high  drill 
speed  without  turning  the  handle  too  fast.  A  small  hand 
drill  is  shown  at  Fig.  167,  A.  As  will  be  observed,  the 
chuck  spindle  is  driven  by  a  small  bevel  pinion,  which  in 
turn,  is  operated  by  a  large  bevel  gear  turned  by  a  crank. 
The  gear  ratio  is  such  that  one  turn  of  the  handle  will 
turn  the  chuck  five  or  six  revolutions.  A  drill  of  this 
design  is  not  suited  for  drills  any  larger  than  one-quarter 
inch.  For  use  with  drills  ranging  from  one-eighth  to 
three-eighths,  or  even  half -inch  the  hand  drill  presses 
shown  at  C  and  D  are  used.  These  have  a  pad  at  the 
upper  end  by  which  pressure  may  be  exerted  with  the 
chest  in  order  to  feed  the  drill  into  the  work,  and  for 
this  reason  they  are  termed  "breast  drills."  The  form 
at  C  has  compound  gearing,  the  drill  chuck  being  driven 
by  the  usual  form  of  bevel  pinion  in  mesh  with  a  larger 
bevel  gear  at  one  end  of  a  countershaft.  A  small  helical 
spur  pinion  at  the  other  end  of  this  countershaft  receives 
its  motion  from  a  larger  gear  turned  by  the  hand  crank. 
This  arrangement  of  gearing  permits  of  high  spindle 
speed  without  the  use  of  large  gears,  as  would  be  neces- 


Drilling  Machines 


387 


sary  if  but  two  were  used.  The  form  at  D  gives  two 
speeds,  one  for  use  with  small  drills  is  obtained  by  en- 
gaging the  lower  bevel  pinion  with  the  chuck  spindle  and 


CHUCK 


Fig.  167.— Forms  of  Hand  Operated  DriUing  Machines. 

driving  it  by  the  large  ring  gear.  The  slow  speed  is  ob- 
tained by  shifting  the  clutch  so  that  the  top  bevel  pinion 
drives  the  drill  chuck.  As  this  meshes  with  a  gear  but 
slightly  larger  in  diameter,  a  slow  speed  of  the  drill 
chuck  is  possible.  Breast  drills  are  provided  with  a 


388  Aviation  Engines 

handle  screwed  into  the  side  of  the  frame,  these  are  used 
to  steady  the  drill  press.  For  drilling  extremely  large 
holes  which  are  beyond  the  capacity  of  the  usual  form 
of  drill  press  the  ratchet  form  shown  at  B,  may  be  used 
or  the  bit  brace  outlined  at  E.  The  drills  used  with  either 
of  these  have  square  shanks,  whereas  those  used  in  the 
drill  presses  have  round  shanks.  The  bit  brace  is  also 
used  widely  in  wood  work  and  the  form  shown  is  provided 
with  a  ratchet  by  which  the  bit  chuck  may  be  turned 
through  only  a  portion  of  a  revolution  in  either  direction 
if  desired. 

DRILLS,   REAMERS,   TAPS  AND   DIES 

In  addition  to  the  larger  machine  tools  and  the  simple 
hand  tools  previously  described,  an  essential  item  of  equip- 
ment of  any  engine  or  plane  repair  shop,  even  in  cases 
where  the  ordinary  machine  tools  are  not  provided,  is  a 
complete  outfit  of  drills,  reamers,  and  threading  tools. 
Drills  are  of  .two  general  classes,  the  flat  and  the  twist 
drills.  The  flat  drill  has  an  angle  between  cutting  edges 
of  about  110  degrees  and  is  usually  made  from  special 
steel  commercially  known  as  drill  rod. 

A  flat  drill  cannot  be  fed  into  the  work  very  fast  be- 
cause it  removes  metal  by  a  scraping,  rather  than  a 
cutting  process.  The  twist  drill  in  its  simplest  form  is 
cylindrical  throughout  the  entire  length  and  has  spiral 
flutes  which  are  ground  off  at  the  end  to  form  the  cutting 
lip  and  which  also  serve  to  carry  the  metal  chips  out  of 
the  holes.  The  simplest  form  of  twist  drill  used  is  shown 
at  Fig.  168,  C,  and  is  known  as  a  " chuck"  drill,  because 
it  must  be  placed  in  a  suitable  chuck  to  turn  it.  A  twist 
drill  removes  metal  by  cutting  and  it  is  not  necessary  to 
use  a  heavy  feed  as  the  drill  will  tend  to  feed  itself  into 
the  work. 

Larger  drills  than  %-inch  are  usually  made  with  a 
tapered  shank  as  shown  at  Fig.  168,  B.  At  the  end  of 
the  taper  a  tongue  is  formed  which  engages  with  a  suit- 
able opening  in  the  collet,  as  the  piece  used  to  support 


Drills  and  Reamers 


389 


the  drill  is  called.  The  object  of  this  tongue  is  to  relieve 
the  tapered  portion  of  the  drill  from  the  stress  of  driving 
by  frictional  contact  alone,  as  this  would  not  turn  the 
drill  positively  and  the  resulting  slippage  would  wear  the 
socket,  .this  depreciation  changing  the  taper  and  making 
it  unfit  for  other  drills.  The  tongue  is  usually  propor- 
tioned so  it  is  adequate  to  drive  the  drill  under  any  con- 


Fig.  168. — Forms  of  Drills  Used  in  Hand  and  Power  Drilling  Machines. 

dition.  A  small  keyway  is  provided  in  the  collet  into  which 
a  tapering  key  of  flat  stock  may  be  driven  against  the 
end  of  the  tongue  to  drive  the  drill  from  the  spindle.  A 
standard  taper  for  drill  shanks  generally  accepted  by  the 
machine  trade  is  known  as  the  Morse  and  is  a  taper  of 
five-eighths  of  an  inch  to  the  foot.  The  Brown  and  Sharp 
form  tapers  six-tenths  of  an  inch  to  the  foot.  Care  must 
be  taken,  therefore,  when  purchasing  drills  and  collets, 


390  Aviation  Engines 

to  make  sure  that  the  tapers  coincide,  as  no  attempt 
should  be  made  to  run  a  Morse  taper  in  a  Brown  and 
Sharp  collet,  or  vice  versa. 

Sometimes  cylindrical  drills  have  straight  flutes,  as 
outlined  at  Fig.  168,  A.  Such  drills  are  used  with  soft 
metals  and  are  of  value  when  the  drill  is  to  pass  entirely 
through  the  work.  The  trouble  with  a  drill  with  spiral 
flutes  is  that  it  will  tend  to  draw  itself  through  as  the 
cutting  lips  break  through.  This  catching  of  the  drill 
may  break  it  or  move  the  work  from  its  position.  With 
a  straight  flute  drill  the  cutting  action  is  practically  the 
same  as  with  the  flat  drill  shown  at  Fig.  168,  E  and  F. 

If  a  drill  is  employed  in  boring  holes  through  close- 
grained,  tough  metals,  as  wrought  or  malleable  iron  and 
steel,  the  operation  will  be  facilitated  by  lubricating  the 
drill  with  plenty  of  lard  oil  or  a  solution  of  soda  and 
water. .  Either  of  these  materials  will  effectually  remove 
the  heat  caused  by  the  friction  of  the  metal  removed 
against  the  lips  of  the  drill,  and  the  danger  of  heating 
the  drill  to  a  temperature  that  will  soften  it  by  drawing 
the  temper  is  minimized.  In  drilling  large  or  deep  holes 
it  is  good  practice  to  apply  the  lubricating  medium  di- 
rectly at  the  drill  point.  Special  drills  of  the  form  shown 
at  Fig.  62,  D,  having  a  spiral  oil  tube  running  in  a 
suitably  formed  channel,  provides  communication  between 
the  point  of  the  drill  and  a  suitable  receiving  hole  on  a 
drilled  shank.  The  oil  is  supplied  by  a  pump  and  its 
pressure  not  only  promotes  positive  circulation  and  re- 
moval of  heat,  but  also  assists  in  keeping  the  hole  free 
of  chips.  In  drilling  steel  or  wrought  iron,  lard  oil 
applied  to  the  point  of  the  drill  will  facilitate  the  drill- 
ing, but  this  material  should  never  be  used  with  either 
brass  or  cast  iron. 

The  sizes  to  be  provided  depend  upon  the  nature  of 
the  work  and  the  amount  of  money  that  can  be  invested 
in  drills.  It  is  common  practice  to  provide  a  set  of  drills, 
such  as  shown  at  Fig.  169,  which  are  carried  in  a  suitable 
metal  stand,  these  being  known  as  number  drills  on  ac- 


Drills  and  Reamers 


391 


count  of  conforming  to  the  wire  gauge  standards.  Num- 
ber drills  do  not  usually  run  higher  than  %6  inch  in 
diameter.  Beyond  this  point  drills  are  usually  sold  by 
the  diameter.  A  set  of  chuck  drills,  ranging  from  %  to 
%  inch,  advancing  by  %2  inch,  and  a  set  of  Morse  taper 
shank  drills  ranging  from  %  to  l1^  inches,  by  increments 
of  Vis  inch,  will  be  all  that  is  needed  for  the  most  pre- 
tentious repair  shop,  as  it  is  cheaper  to  bore  holes  larger 
than  1%  inches  with  a  boring  tool  than  it  is  to  carry  a 


1 


Fig.  169.— Useful  Set  of  Number  Drills,  Showing  Stand  for  Keeping  These 
in  an  Orderly  Manner. 

number  of  large  drills  in  stock  that  would  be  used  very 
seldom,  perhaps  not  enough  to  justify  their  cost. 

In  grinding  drills,  care  must  be  taken  to  have  the 
lips  of  the  same  length,  so  that  they  will  form  the  same 
angle  with  the  axis.  If  one  lip  is  longer  than  the  other, 
as  shown  in  the  flat  drill  at  Fig.  168,  E,  the  hole  will  be 
larger  than  the  drill  size,  and  all  the  work  of  cutting  will 
come  upon,  the  longest  lip.  The  drill  ends  should  be  sym- 
metrical, as  shown  at  Fig.  168,  F. 

It  is  considered  very  difficult  to  drill  a  hole  to  an  exact 
diameter,  but  for  the  most  work  a  variation  of  a  few 
thousandths  of  an  inch  is  of  no  great  moment.  Where 
accuracy  is  necessary,  holes  must  be  reamed  out  to  the 
required  size.  In  reaming,  a  hole  is  drilled  about  %2  inch 


392 


Aviation  Engines 


smaller  than  is  required,  and  is  enlarged  with  a  cutting 
tool  known  as  the  reamer.  Eeamers  are  usually  of  the 
fluted  form  shown  at  Fig.  170,  A.  Tools  of  this  nature 
are  not  designed  to  remove  considerable  amounts  of 
metal,  but  are  intended  to  augment  the  diameter  of  the 
drill  hole  by  only  a  small  fraction  of  an  inch.  Eeamers 


B 


1  C 


D 


§31 


1 


Fig.  170. — Illustrating  Standard  Forms  of  Hand  and  Machine  Eeamers. 

are  tapered  slightly  at  the  point  in  order  that  they  will 
enter  the  hole  easily,  but  the  greater  portion  of  the  fluted 
part  is  straight,  all  cutting  edges  being  parallel.  Hand 
reamers  are  made  in  either  the  straight  or  taper  forms, 
that  at  A,  Fig.  170,  being  straight,  while  B  has  tapering 
flutes.  They  are  intended  to  be  turned  by  a  wrench  simi- 
lar to  that  employed  in  turning  a  tap,  as  shown  at  Fig. 


Types  of  Reamers  and  Use  393 

172,  C.  The  reamer  shown  at  Fig.  170,  C,  is  a  hand 
reamer.  The  form  at  D  has  spiral  flutes  similar  to  a 
twist  drill,  and  as  it  is  provided  with  a  taper  shank  it  is 
intended  to  be  turned  by  power  through  the  medium  of 
a  suitable  collet. 

As  the  solid  reamers  must  become  reduced  in  size 
when  sharpened,  various  forms  of  inserted  blade  reamers 
have  been  designed.  One  of  these  is  shown  at  E,  and  as 
the  cutting  surfaces  become  reduced  in  diameter  it  is 
possible  to  replace  the  worn  blades  with  others  of  proper 
size.  Expanding  reamers  are  of  the  form  shown  at  F. 
These  have  a  bolt  passing  through  that  fits  into  a  taper- 
ing hole  in  the  interior  of  the  split  reamer  portion  of  the 
tool.  If  the  hole  is  to  be  enlarged  a  few  thousandths  of 
an  inch,  it  is  possible  to  draw  up  on  the  nut  just  above 
the  squared  end  .of  the  shank,  and  by  drawing  the  taper- 
ing wedge  farther  into  the  reamer  body,  the  cutting  por- 
tion will  be  expanded  and  will  cut  a  larger  hole. 

Eeamers  must  be  very  carefully  sharpened  or  there 
will  be  a  tendency  toward  chattering  with  a  consequent 
production  of  a  rough  surface.  There  are  several  methods 
of  preventing  this  chattering,  one  being  to  separate  the 
cutting  edges  by  irregular  spaces,  wrhile  the  most  common 
method,  and  that  to  be  preferred  on  machine  reamers,  is 
to  use  spiral  flutes,  as  shown  at  Fig.  170,  D.  Special 
taper  reamers  are  made  to  conform  to  the  various  taper 
pin  sizes  which  are  sometimes  used  in  holding  parts  to- 
gether in  an  engine.  A  taper  of  %e  inch  per  foot  is  in- 
tended for  holes  where  a  pin,  once  driven  in,  is  to  remain 
in  place.  "When  "it  is  desired  that  the  pin  be  driven  out, 
the  taper  is  made  steeper,  generally  14  inc^  Per  foot, 
which  is  the  standard  taper  used  on  taper  pins. 

When  threads  are  to  be  cut  in  a  small  hole,  it  will  be 
apparent  that  it  will  be  difficult  to  perform  this  operation 
economically  on  a  lathe,  therefore  when  internal  thread- 
ing is  called  for,  a  simple  device  known  as  a  "tap"  is 
used.  There  are  many  styles  of  taps,  all  conforming  to 
different  standards.  Some  are  for  metric  or  foreign 


394 


Aviation  Engines 


threads,  some  conform  to  the  American  standards,  while 
others  are  nsed  for  pipe  and  tubing.  Hand  taps  are  the 
form  most  used  in  repair  shops,  these  being  outlined  at 
Fig.  171,  A  and  B.  They  are  usually  sold  in  sets  of  three, 
known  respectively  as  taper,  plug,  and  bottoming.  The 
taper  tap  is  the  one  first  put  into  the  hole,  and  is  then 
followed  by  the  plug  tap  which  cuts  the  threads  deeper. 


fl 


Fig.  171.— Tools  for  Thread  Cutting. 

If  it  is  imperative  that  the  thread  should  be  full  size 
clear  to  the  bottom  of  the  hole,  the  third  tap  of  the  set, 
which  is  straight-sided,  is  used.  It  would  be  difficult  to 
start  a  bottoming  tap  into  a  hole  because  it  would  be 
larger  in  diameter  at  its  point  than  the  hole.  The  taper 
tap,  as  shown  at  A,  Fig.  171,  has  a  portion  of  the  cutting 
lands  ground  away  at  the  point  in  order  that  it  will  enter 
the  hole.  The  manipulation  of  a  tap  is  not  hard,  as  it 
does  not  need  to  be  forced  into  the  work,  as  the  thread 


Use  of  Taps  and  Dies  395 

will  draw  it  into  the  hole  as  the  tap  is  turned.  The 
tapering  of  a  tap  is  done  so  that  no  one  thread  is  called 
upon  to  remove  all  of  the  metal,  as  for  about  half  way  up 
the  length  of  the  tap  each  succeeding  thread  is  cut  a 
little  larger  by  the  cutting  edge  until  the  full  thread 
enters  the  hole.  Care  must  be  taken  to  always  enter  a 
tap  straight  in  order  to  have  the  thread  at  correct  angles 
to  the  surface. 

In  cutting  external  threads  on  small  rods  or  on  small 
pieces,  such  as  bolts  and  studs,  it  is  not  always  economi- 
cal to  do  this  work  in  the  lathe,  especially  in  repair  work. 
Dies  are  used  to  cut  threads  on  pieces  that  are  to  be 
placed  in  tapped  holes  that  have  been  threaded  by  the 
corresponding  size  of  tap.  Dies  for  small  work  are  often 
made  solid,  as  shown  at  Fig.  171,  C,  but  solid  dies  are 
usually  limited  to  sizes  below  y2  inch.  Sometimes  the 
solid  die  is  cylindrical  in  shape,  with  a  slot  through 
one  side  which  enables  one  to  obtain  a  slight  degree  of 
adjustment  by  squeezing  the  slotted  portion  together. 
Large  dies,  or  the  sizes  over  y2  inch,  are  usually  made 
in  two  piece's  in  order  that  the  halves  may  be  closed  up 
or  brought  nearer  together.  The  advantage  of  this  form 
of  die  is  that  either  of  the  two  pieces  may  be  easily  sharp- 
ened, and  as  it  may  be  adjusted  very  easily  the  thread 
may  be  cut  by  easy  stages.  For  example,  the  die  may  be 
adjusted  to  cut  large,  which  will  produce  a  shallow  thread 
that  will  act  as  an  accurate  guide  when  the  die  is  closed 
up  and  a  deeper  thread  cut. 

A  common  form  of  die  holder  for  an  adjustable  die  is 
shown  at  Fig.  172,  A.  As  will  be  apparent,  it  consists 
pf  a  central  body  portion  having  guide  members  to  keep 
the  die  pieces  from  falling  out  and  levers  at  each  end  in 
order  to  permit  the  operator  to  exert  sufficient  force  to 
remove  the  metal.  The  method  of  adjusting  the  depth  of 
thread  with  a  clamp  screw  when  a  two-piece  die  is  em- 
ployed is  also  clearly  outlined.  The  die  stock  shown  at 
B  is  used  for  the  smaller  dies  of  the  one-piece  pattern, 
having  a  slot  in  order  that  they  may  be  closed  up  slightly 


396 


Aviation  Engines 


by  the  clamp  screw.  The  reverse  side  of  the  diestock 
shown  at  B  is  outlined  below  it,  and  the  guide  pieces, 
which  may  be  easily  moved  in  or  out,  according  to  the 
size  of  the  piece  to  be  threaded  by  means  of  eccentrically 
disposed  semi-circular  slots  in  the  adjustment  plate,  are 


Fig.  172. — Showing  Holder  Designs  for  One-  and  Two-Piece  Thread  Cutting 

Dies. 

shown.  These  movable  guide  members  have  small  pins 
let  into  their  surface  ^hich  engage  the  slots,  and  they 
may  be  moved  in  or  out,  as  desired,  according  to  the  posi- 
tion of  the  adjusting  plate.  The  use  of  the  guide  pieces 
makes  for  accurate  positioning  or  centering  of  the  rod  to 
be  threaded.  Dies  are  usually  sold  in  sets,  and  are  com- 
monly furnished  as  a  portion  of  a  complete  outfit  such  as 


Measuring  Tools 


397 


outlined  at  Fig.  173.  That  shown  has  two  sizes  of  die- 
stock,  a  tap  wrench,  eight  assorted  dies,  eight  assorted 
taps,  and  a  small  screw  driver  for  adjusting  the  die.  An 
automobile  repair  shop  should  be  provided  with  three 
different  sets  of  taps  and  dies,  as  three  different  stand- 
ards for  the  bolts  and  nuts  are  used  in  fastening  auto- 
mobile components.  These  are  the  American,  metric 


Fig.  173. — Useful  Outfit  of  Taps  and  Dies  for  the  Engine  Repair  Shop. 

(used  on  foreign  engines),  and  the  S.  A.  E.  standard 
threads.  A  set  of  pipe  dies  and  taps  will  also  be  found 
useful. 

MEASURING   TOOLS 

The  tool  outfit  of  the  machinist  or  the  mechanic  who 
aspires  to  do  machine  work  must  include  a  number  of 
measuring  tools  which  are  not  needed  by  the  floor  man  or 
one  who  merely  assembles  and  takes  apart  the  finished 
pieces.  The  machinist  who  must  convert  raw  material 
into  finished  products  requires  a  number  of  measuring 
tools,  some  of  which  are  used  for  taking  only  approxi- 
mate measurements,  such  as  calipers  and  scales,  while 
others  are  intended  to  take  very  accurate  measurements, 
such  as  the  Vernier  and  the  micrometer.  A  number  of 
common  forms  of  calipers  are  shown  at  Fig.  174.  These 
are  known  as  inside  or  outside  calipers,  depending  upon 
the  measurements  they  are  intended  to  take.  That  at  A 


398 


Aviation  Engines 


is  an  inside  caliper,  consisting  of  two  legs,  A  and  D,  and 
a  gauging  piece,  B,  which  can  be  locked  to  leg  A,  or  re- 
leased from  that  member  by  the  screw,  C.  The  object  of 
this  construction  is  to  permit  of  measurements  being 
taken  at  the  bottom  of  a.  two  diameter  hole,  where  the 
point  to  be  measured  is  of  larger  diameter  than  the  por- 
tion of  the  hole  through  which  the  calipers  entered.  It 
will  be  apparent  that  the  legs  A  and  D  must  be  brought 
close  together  to  pass  through  the  smaller  holes.  This 


Fig.  174. — Common  Forms  of  Inside  and  Outside  Calipers. 

may  be  done  without  losing  the  setting,  as  the  guide  bar 
B  will  remain  in  one  position  as  determined  by  the  size 
of  the  hole  to  be  measured,  while  the  leg  A  may  be  swung 
in  to  clear  the  obstruction  as  the  calipers  are  lifted  out. 
When  it  is  desired  to  ascertain  the  measurements  the  leg 
A  is  pushed  back  into  place  into  the  slotted  portion  of  the 
guide  B,  and  locked  by  the  clamp  screw  C.  A  tool  of  this 
form  is  known  as  an  internal  transfer  caliper. 

The  form  of  caliper  shown  at  B  is  an  outside  caliper. 
Those  at  C  and  D  are  special  forms  for  inside  and  out- 


Measuring  Tools  399 

side  work,  the  former  being  used,  if  desired,  as  a  divider, 
while  the  latter  may  be  employed  for  measuring  the 
walls  of  tubing.  The  calipers  at  E  are  simple  forms, 
having  a  friction  joint  to  distinguish  them  from  the  spring 
calipers  shown  at  B,  C  and  D.  In  order  to  permit  of 
ready  adjustment  of  a  spring  caliper,  a  split  nut  as  shown 
at  G  is  sometimes  used.  A  solid  nut  caliper  can  only  be 
adjusted  by  screwing  the  nut  in  or  out  on  the  screw, 
which  may  be  a  tedious  process  if  the  caliper  is  to  be  set 
from  one  extreme  to  the  other  several  times  in  succession. 
With  a  slip  nut  as  shown  at  Gr  it  is  possible  to  slip  it 
from  one  end  of  the  thread  to  the  other  without  turning 
it,  and  of  locking  it  in  place  at  any  desired  point  by 
simply  allowing  the  caliper  leg  to  come  in  contact  with 
it.  The  method  of  adjusting  a  spring  caliper  is  shown 
at  Fig.  174,  H. 

Among  the  most  common  of  the  machinist's  tools  are 
those  used  for  linear  measurements.  The  usual  forms  are 
shown  in  group,  Fig.  175.  The  most  common  tool,  which 
is  widely  known,  is  the  carpenter's  folding  two-foot  rule 
or  the  yardstick.  While  these  are  very  convenient  for 
taking  measurements  where  great  accuracy  is  not  re- 
quired, the  machinist  must  work  much  more  accurately 
than  the  carpenter,  and  the  standard  steel  scale  which  is 
shown  at  D,  is  a  popular  tool  for  the  machinist.  The 
steel  scale  is  in  reality  a  graduated  straight  edge  and 
forms  an  important  part  of  various  measuring  tools. 
These  are  made  of  high  grade  steel  and  vary  from  1  to 
48  inches  in  length.  They  are  carefully  hardened  in  order 
to  preserve  the  graduations,  and  all  surfaces  and  edges 
are  accurately  ground  to  insure  absolute  parallelism.  The 
graduations  on  the  high  grade  scales  are  produced  with 
a  special  device  known  as  a  dividing  engine,  but  on 
cheaper  scales,  etching  suffices  to  provide  a  fairly  accurate 
graduation.  The  steel  scales  may  be  very  thin  and  flex- 
ible, or  may  be  about  an  eighth  of  an  inch  thick  on  the 
twelve-inch  size,  which  is  that  commonly  used  with  com- 
bination squares,  protractors  and  other  tools  of  that, 


400 


Aviation  Engines 


nature.  The  repairrnan's  scale  should  be  graduated  both 
with  the  English  system,  in  which  the  inches  are  di- 
vided into  eighths,  sixteenths,  thirty-secondths  and  sixty- 


1  2  3  4.  5. 

il.i.l.i.lii.l.i.lililililiiiliiil.iif.i.l.i. 


rij    il  i 


91 '    3 

i  h  I  ill 


i  h 


Fig.  175. — Measuring  Appliances  for  the  Machinist  and  Floor  Man. 

fourths,  and  also  in  the  metric  system,  divided  into  milli- 
meters and  centimeters.  Some  machinists  use  scales 
graduated  in  tenths,  twentieths,  fiftieths  and  hundredths. 


Measuring  Instruments  401 

This  is  not  as  good  a  system  of  graduation  as  the  more 
conventional  one  first  described. 

Some  steel  scales  are  provided  with  a  slot  or  groove 
cut  the  entire  length  on  one  side  and  about  the  center  of 
the  scales.  This  permits  the  attachment  of  various  fit- 
tings such  as  the  protractor  head,  which  enables  the  ma- 
chinist to  measure  angles,  or  in  addition  the  heads  convert 
the  scale  into  a  square  or  a  tool  permitting  the  accurate 
bisecting  of  pieces  of  circular  section.  Two  scales  are 
sometimes  joined  together  to  form  a  right  angle,  such  as 
shown  at  Fig.  175,  C.  This  is  known  as  a  square  and  is 
very  valuable  in  ascertaining  the  truth  of  vertical  pieces 
that  are  supposed  to  form  a  right  angle  with  a  base  piece. 

The  Vernier  is  a  device  for  reading  finer  divisions  on 
a  scale  than  those  into  which  the  scale  is  divided.  Sixty- 
fourths  of  an  inch  are  about  the  finest  division  that  can 
be  read  accurately  with  the  naked  eye.  When  fine  work 
is  necessary  a  Vernier  is  employed.  This  consists  essen- 
tially of  two  rules  so  graduated  that  the  true  scale  has 
each  inch  divided  into  ten  equal  parts,  the  upper  or  Ver- 
nier portion  has  ten  divisions  occupying  the  same  space 
as  nine  of  the  divisions  of  the  true  scale.  It  is  evident, 
therefore,  that  one  of  the  divisions  of  the  Vernier  is  equal 
to  nine-tenths  of  one  of  those  on  the  true  scale.  If  the 
Vernier  scale  is  moved  to  the  right  so  that  the  gradua- 
tions marked  '  *  1 ' '  shall  "coincide,  it  will  have  moved  one- 
tenth  of  a  division  on  the  scale  or  one-hundredth  of  an 
inch.  When  the  graduations  numbered  5  coincide  the 
Vernier  will  have  moved  five-hundredths  of  an  inch ;  when 
the  lines  marked  0  and  10  coincide,  the  Vernier  will  have 
moved  nine-hundredths  of  an  inch,  and  when  10  on  the 
Vernier  comes  opposite  10  on  the  scales,  the  upper  rule 
will  have  moved  ten-hundredths  of  an  inch,  or  the  whole 
of  one  division  on  the  scale.  By  this  means  the  scale, 
though  it  may  be  graduated  only  to  tenths  of  an  inch, 
may  be  accurately  set  at  points  with  positions  expressed 
in  hundredths  of  an  inch.  When  graduated  to  read  in 
thousandths,  the  true  scale  is  divided  into  fifty  parts  and 


402 


Aviation  Engines 


the  Vernier  into  twenty  parts.  Each  division  of  the  Ver- 
nier is  therefore  equal  to  nineteen-twentieths  of  one  of 
the  true  scale.  If  the  Vernier  be  moved  so  the  lines  of 
the  first  division  coincide,  it  will  have  moved  one-twen- 
tieth of  one-fiftieth,  or  .001  inch.  The  Vernier  principle 
can  be  readily  grasped  by  studying  the  section  of  the 
Vernier  scale  and  true  scale  shown  at  Fig.  176,  A. 

The  caliper  scale  which  is  shown  at  Fig.  175,  A,  per- 
mits of  taking  the  over-all  dimension  of  any  parts  that 


5lN. 


Fig.  176.— At  Left,  Special  Form  of  Vernier  Calipeff  for  Measuring  Gea* 
Teeth;  at  Right,  Micrometer  for  Accurate  Internal  Measurements. 

will  go  between  the  jaws.  This  scale  can  be  adjusted  very 
accurately  by  means  of  a  fine  thread  screw  attached  to  a 
movable  jaw  and  the  divisions  may  be  divided  by  eye 
into  two  parts  if  one  sixty-fourth  is  the  smallest  of  the 
divisions.  A  line  is  indicated  on  the  movable  jaw  and 
coincides  with  the  graduations  on  the  scale.  As  will  be 
apparent,  if  the  line  does  not  coincide  exactly  with  one 
of  the  graduations  it  will  be  at  some  point  between  the 
lines  and  the  true  measurement  may  be  approximated  with- 
out trouble. 

A  group  of  various  other  measuring  tools  of  value  to 
the  machinist  is  shown  at  Fig;  177.  The  small  scale  at  A 
is  termed  a  "center  gauge,"  because  it  can  be  used  to  test 


Measuring  Tools 


403 


the  truth  of  the  taper  of  either  a  male  or  female  lathe 
center.  The  two  smaller  nicks,  or  v's,  indicate  the  shape 
of  a  standard  thread,  and  may  be  used  as  a  guide  for 
grinding  the  point  of  a  thread-cutting  tool.  The  cross 
level  which  is  showyn  at  B  is  of  marked  utility  in  erecting, 
as  it  will  indicate  absolutely  if  the  piece  it  is  used  to  test 


Fig.  177. — Measuring  Appliances  of  Value  in  Airplane  Repair  Work. 

is  level.     It  will  indicate  if  the  piece  is  level '  along  its 
width  as  well  as  its  length. 

A  very  simple  attachment  for  use  with  a  scale  that 
enables  the  machinist  to  scribe  lines  along  the  length  of 
a  cylindrical  piece  is  shown  at  Fig.  177,  C.  These  are 
merely  small  wedge-shaped  clamps  having  an  angular 
face  to  rest  upon  the  bars.  The  thread  pitch  gauge  which 
is  shown  at  Fig.  177,  D,  is  an  excellent  pocket  tool  for  the 
mechanic,  as  it  is  often  necessary  to  determine  without 
loss  of  time  the  pitch  of  the  thread  on  a  bolt  or  in  a  nut. 
This  consists  of  a  number  of  leaves  having  serrations  on 
one  edge  corresponding  to  the  standard  thread  it  is  to  be 


404  Aviation  Engines 

used  in  measuring.  The  tool  shown  gives  all  pitches  up 
to  48  threads  per  inch.  The  leaves  may  be  folded  in  out 
of  the  way  when  not  in  use,  and  their  shape  admits  of 
their  being  used  in  any  position  without  the  remainder 
of  the  set  interfering  with  the  one  in  use.  The  fine  pitch 
gauges  have. slim,  tapering  leaves  of  the  correct  shape  to 
be  used  in  finding  the  pitch  of  small  nuts.  As  the  tool  is 
round  when  the  leaves  are  folded  back  out  of  the  way,  it 
is  an  excellent  pocket  tool,  as  there  are  no  sharp  corners 
to  wear  out  the  pocket.  Practical  application  of  a  Ver- 
nier having  measuring  heads  of  special  form  for  measur- 
ing gear  teeth  is  shown  at  Fig.  176,  A.  As  the  action  of 
this  tool  has  been  previously  explained,  it  will  not  be 
necessary  to  describe  it  further. 


MICROMETER   CALIPERS   AND   THEIR   USE 

Where  great  accuracy  is  necessary  in  taking  measure- 
ments the  micrometer  caliper,  which  in  the  simple  form 
will  measure  easily  .001  inch  (one-thousandth  part  of  an 
inch)  and  when  fitted  with  a  Vernier  that  will  measure 
.0001  inch  (one  ten- thousandth  part  of  an  inch),  is  used. 
The  micrometer  may  be  of  the  caliper  form  for  measur- 
ing outside  diameters  or  it  may  be  of  the  form  shown  at 
Fig.  176,  B,  for  measuring  internal  diameters.  The  opera- 
tion of  both  forms  is  identical  except  that  the  internal 
micrometer  is  placed  inside  of  the  bore  to  be  measured 
while  the  external  form  is  used  just  the  same  as  a  caliper. 
The  form  outlined  will  measure  from  one  and  one-half  to 
six  and  a  half  inches  as  extension  points  are  provided  to 
increase  the  range  of  the  instrument.  The  screw  has  a 
movement  of  one-half  inch  and  a  hardened  anvil  is  placed 
in  the  end  of  the  thimble  in  order  to  prevent  undue  wear 
at  that  point.  The  extension  points  or  rods  are  accurately 
made  in  standard  lengths  and  are  screwed  into  the  body 
of  the  instrument  instead  of  being  pushed  in,  this  insur- 
ing firmness  and  accuracy.  Two  forms  of  micrometers 
for  external  measurements  are  shown  at  Fig.  178.  The 


Micrometers  and  Their  Use 


405 


top  one  is  graduated  to  read  in  thousandths  of  an  inch, 
while  the  lower  one  is  graduated  to  indicate  hundredths 
of  a  millimeter.  The  mechanical  principle  involved  in  the 
construction  of  a  micrometer  is  that  of  a  screw  free  to 


Oevefojxntrit of 
Sco/e  on  Qoml 
of  Inch  Micrometer 


fin 


of 

<Scof6   on   Borre/ 
of  Afefa'c  Micrometer 


Tig.  178. — Standard  Forms  of  Micrometer  Caliper  for  External  Measure- 
ments. 

move  in  a  fixed  nut.  An  opening  to  receive  the  work  to 
be  measured  is  provided  by  the  backward  movement  of  the 
thimble  which  turns  the  screw  and  the  size  of  the  opening 
is  indicated  by  the  graduations  on  the  barrel. 


406  Aviation  Engines 

The  article  to  be  measured  is  placed  between  the  anvil 
and  spindle,  the  frame  being  held  stationary  while  the 
thimble  is  revolved  by  the  thumb  and  finger.  The  pitch 
of  the  screw  thread  on  the  concealed  part  of  the  spindle 
is  40  to  an  inch.  One  complete  revolution  of  the  spindle, 
therefore,  moves  it  longitudinally  one-fortieth,  or  twenty- 
five  thousandths  of  an  inch.  As  will  be  evident  from  the 
development  of  the  scale  on  the  barrel  of  the  inch  mi- 
crometer, the  sleeve  is.  marked  with  forty  lines  to  the 
inch,  each  of  these  lines  indicating  twenty-five  thou- 
sandths. .  The  thimble  has  a  beveled  edge  which  is  gradu- 
ated into  twenty-five  parts.  When  the  instrument  is 
closed  the  graduation  on  the  beveled  edge  of  the  thimble 
marked  0  should  correspond  to  the  0  line  on  the  barrel. 
If  the  micrometer  is  rotated  one  full  turn  the  opening 
between  the  spindle  and  anvil  will  be  .025  inch.  If  the 
thimble  is  turned  only  one  graduation,  or  one  twenty- 
fifth  of  a  revolution,  the  opening  between  the  spindle  and 
anvil  will  be  increased  only  by  .001  inch,  (one-thousandth 
of  an  inch). 

As  many  of  the  dimensions  of  the  airplane  parts, 
especially  of  those  of  foreign  manufacture  or  such  parts 
as  ball  and  roller  bearings,  are  based  on  the  metric  sys- 
tem, the  competent  repairman  should  possess  both  inch 
and  metric  micrometers  in  order  to  avoid  continual  refer- 
ence to  a  table  of  metric  equivalents.  With  a  metric  mi- 
crometer there  are  fifty  graduations  on  the  barrel,  these 
representing  .01  of  a  millimeter,  or  approximately  .004 
inch.  One  full  turn  of  the  barrel  means  an  increase  of 
half  a  millimeter,  or  .50  mm.  (fifty  one-hundredths).  As 
it  takes  two  turns  to  augment  the  space  between  the  anvil 
and  the  stem  by  increments  of  one  millimeter,  it  will  be 
evident  that  it  would  not  be  difficult  to  divide  the  spaces 
on  the  metric  micrometer  thimble  in  halves  by  the  eye, 
and  thus  the  average  workman  can  measure  to  .0002  inch 
plus  or  minus  without  difficulty.  As  set  in  the  illustra- 
tion, the  metric  micrometers  show  a  space  of  13.5  mm., 
or  about  one  millimeter  more  than  half  an  inch.  The 


Micrometers  and  Their  Use  407 

inch,  micrometer  shown  is  set  to  five-tenths  or  five  hun- 
dred one-thousandths  or  one-half  inch.  A  little  study  of 
the  foregoing  matter  will  make  if  easy  to  understand  th( 
action  of  either  the  inch  or  metric  micrometer. 

Both  of  the  micrometers  shown  have  a  small  knurled 
knob  at  the  end  of  the  barrel.  This  controls  the  ratchet 
stop,  which  is  a  device  that  permits  a  ratchet  to  slip  by 
a  pawl  when  more  than  a  certain  amount  of  pressure  is 
applied,  thereby  preventing  the  measuring  spindle  from 
turning  further  and  perhaps  springing  the  instrument.  A 
simple  rule  that  can  be  easily  memorized  for  reading  the 
"inch  micrometer  is  to  multiply  the  number  of  vertical 
divisions  on  the  sleeve  by  25  and  add  to  that  the  number 
of  divisions  on  the  bevel  of  the  thimble  reading  from  the 
zero  to  the  line  which  coincides  with  the  horizontal  line  on 
the  sleeve.  For  example:  if  there  are  ten  divisions  visi- 
ble on  the  sleeve,  multiply  this  number  by  25,  then  add 
the  number  of  divisions  shown  on  the  bevel  of  the  thim- 
ble, which  is  10.  The  micrometer  is  therefore  opened 
10x25  equals  250  plus  10  equals  260  thousandths. 

Micrometers  are  made  in  many  sizes,  ranging  from 
those  having  a  maximum  opening  of  one  inch  to  special 
large  forms  that  will  measure  forty  or  more  inches. 
While  it  is  not  to  be  expected  that  the  repairman  will  have 
use  for  the  big  sizes,  if  a  caliper  having  a  maximum 
opening  of  six  inches  is  provided  with  a  number  of  ex- 
tension rods  enabling  one  to  measure  smaller  objects, 
practically  all  of  the  measuring  needed  in  repairing  en- 
gine parts  can  be  made  accurately.  Two  or  three  smaller 
micrometers  having  a  maximum  range  of  two  or  three 
inches  will  also  be  found  valuable,  as  most  of  the  measure- 
ments will  be  made  with  these  tools  which  will  be  much 
easier  to  handle  than  the  larger  sizes. 

TYPICAL   TOOL   OUTFITS 

The  equipment  of  tools  necessary  for  repairing  air- 
plane engines  depends  entirely  upon  the  type  of  the  power 


408  Aviation  Engines 

plant  and  while  the  common  hand  tools  can  be  used  on 
all  forms,  the  work  is  always  facilitated  by  having  special 
tools  adapted  for  reaching  the  nuts  and  screws  that  would 
be  hard  to  reach  otherwise.  Special  spanners  and  socket 
wrenches  are  very  desirable.  Then  again,  the  nature  of 
the  work  to  be  performed  must  be  taken  into  considera- 
tion. Eebuilding  or  overhauling  an  engine  calls  for  con- 
siderably more  tools  than  are  furnished  for  making  field 
repairs  or  minor  adjustments.  A  complete  set  of  tools 
supplied  to  men  working  on  Curtiss  OX-2  engines  and 
JN-4  training  biplanes  is  shown  at  Fig.  179.  The  tools 
are  placed  in  a  special  box  provided  with  a  hinged  cover 
and  are  arranged  in  the  systematic  manner  outlined. 
The  various  tools  and  supplies  shown  are:  A,  hacksaw 
blades;  B,  special  socket  wrenches  for  engine  bolts  and 
nuts;  C,  ball  pein  hammers,  four  sizes;  D,  five  assorted 
sizes  of  screw  drivers  ranging  from  very  long  for  heavy 
work  to  short  and  small  for  fine  work;  -E,  seven  pairs  of 
pliers  including  combination  in  three  sizes,  two  pairs  of 
cutting  pliers  and  one  round  nose;  F,  two  split  pin  ex- 
tractors and  spreaders;  Gr,  wrench  set  including  three, 
adjustable  monkey  wrenches,  one  Stilson  or  pipe  wrench, 
five  sizes  adjustable  end  wrenches  and  ten  double  end 
S  wrenches;  H,  set  of  files,  including  flat,  three  cornered 
and  half  round;  I,  file  brush;  J,  chisel  and  drift  pin; 
K,  three  small  punches  or  drifts;  L,  hacksaw  frame;  M, 
soldering  copper;  N,  special  spanners  for  propeller  re- 
taining nuts;  0,  special  spanners;  P,  socket  wrenches, 
long  handle;  Q,  long  handle,  stiff  bristle  brushes  for 
cleaning  motor;  E,  gasoline  blow  torch;  S,  hand  drill; 
T,  spools  of  safety  wire ;  U,  flash  lamp ;  V,  special  puller 
and  castle  wrenches;  W,  oil  can;  X,  large  adjustable 
monkey  wrench;  Y,  washer  and  gasket  cutter;  Z,  ball  of 
heavy  twine.  In  addition  to  the  tools,  various  supplies, 
such  as  soldering  acid,  solder,  shellac,  valve  grinding  com- 
pound, bolts  and  nuts,  split  pins,  washers,  wood  screws, 
etc.,  are  provided. 


410 


Aviation  Engines 


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412  Aviation  Engines 

The  special  tools  and  fixtures  recommended  by  the 
Hall-Scott  Company  for  work  on  their  engines  are  clearly 
shown  at  Fig.  180.  All  tools  are  numbered  and  their  uses 
may  be  clearly  understood  by  reference  to  the  illustra- 
tion and  explanatory  list  given  on  pages  410  and  411. 


OVERHAULING    AIRPLANE    ENGINES 

After  an  airplane  engine  has  been  in  use  for  a  period 
ranging  from  60  to  80  hours,  depending  upon  the  type, 
it  is  necessary  to  give  it  a  thorough  overhauling  before 
it  is  returned  to  service.  To  do  this  properly,  the  engine 
is  removed  from  the  fuselage  and  placed  on  a  special  sup- 
porting stand,  such  as  shown  at  Fig.  181,  so  it  can  be 
placed  in  any  position  and  completely  dismantled.  With 
a  stand  of  this  kind  it  is  as  easy  to  work  on  the  bottom 
of  the  engine  as  on  the  top  and  every  part  can  be  in- 
stantly reached.  The  crank-case  shown  in  place  in  illus- 
tration is  in  a  very  convenient  position  for  scraping  in 
the  crank-shaft  bearings. 

In  order  to  look  over  the  parts  of  an  engine  and  to 
restore  the  worn  or  defective  components  it  is  necessary 
to  take  the  engine  entirely  apart,  as  it  is  only  when  the 
power  plant  is  thoroughly  dismantled  that  the  parts  can 
be  inspected  or  measured  to  determine  defects  or  wear. 
If  one  is  not  familiar  with  the  engine  to  be  inspected, 
even  though  the  work  is  done  by  a  repairman  of  experi- 
ence, it  will  be  found  of  value  to  take  certain  precautions 
when  dismantling  the  engine  in  order  to  insure  that  all 
parts  will  be  replaced  in  the  same  position  they  occupied 
before  removal.  There  are  a  number  of  ways  of  identi- 
fying the  parts,  one  of  the  simplest  and  surest  being  to 
mark  them  with  steel  numbers  or  letters  or  with  a  series 
of  center  punch  marks  in  order  to  retain  the  proper  rela- 
tion when  reassembling.  -This  is  of  special  importance 
in  connection  with  dismantling  multiple  cylinder  engines 
as  it  is  vital  that  pistons,  piston  rings,  connecting  rods, 
valves,  and  other  cylinder  parts  be  always  replaced  in 


413 


414 


Aviation  Engines 


the  same  cylinder  from  which  they  were  removed,  be- 
cause it  is  uncommon  to  find  equal  depreciation  in  all 
cylinders.  Some  repairmen  use  small  shipping  tags  to 
identify  the  pieces.  This  can  be  criticised  because  the 
tags  may  become  detached  and  lost  and  the  identity  of 


Fig.  181. — Special  Stand  to  Make  Motor  Overhauling  Work  Easier. 

the  piece  mistaken.  If  the  repairing  is  being  done  in  a 
shop  where  other  engines  of  the  same  make  are  being 
worked  on,  the  repairman  should  be  provided  with  a  large 
chest  fitted  with  a  lock  and  key  in  which  all  of  the  smaller 
parts,  such  as  rods,  bolts  and  nuts,  valves,  gears,  valve 
springs,  cam-shafts,  etc.,  may  be  stored  to  prevent  the 
possibility  of  confusion  with  similar  members  of  other 


Dismantling  an  Engine  415 

engines.  All  parts  should  be  thoroughly  cleaned  with 
gasoline  or  in  the  potash  kettle  as  removed,  and  wiped 
clean  and  dry.  This  is  necessary  to  show  wear  which  will 
be  evidenced  by  easily  identified  indications  in  cases 
where  the  machine  has  been  used  for  a  time,  but  in  others, 
the  deterioration  can  only  be  detected  by  delicate  measur- 
ing instruments. 

In  taking  down  a  motor  the  smaller  parts  and  fittings 
such  as  spark-plugs,  manifolds  and  wiring  should  be  re- 
moved first.  Then  the  more  important  members  such  as  cyl- 
inders may  be  removed  from  the  crank-case  to  give  access 
to  the  interior  and  make  possible  the  examination  of  the 
pistons,  rings  and  connecting  rods.  After  the  cylinders  are 
removed  the  next  operation  is  to  disconnect  the  connect- 
ing rods  from  the  crank-shaft  and  to  remove  them  and 
the  pistons  attached  as  a  unit.  Then  the  crank-case  -is 
dismembered,  in  most  cases  by  removing  the  bottom  half 
or  oil  sump,  thus  exposing  the  main  bearings  and  crank- 
shaft. The  first  operation  is  the  removal  of  the  inlet  and 
exhaust  manifolds.  In  some  cases  the  manifolds  are 
cored  integral  with  the  cylinder  head  casting  and  it  is 
merely  necessary  to  remove  a  short  pipe  leading  from  the 
carburetor  to  one  inlet  opening  and  the  exhaust  pipe  from 
the  outlet  opening  common  to  all '  cylinders.  In  order  to 
remove  the  carburetor  it  is  necessary  to  shut  off  the  gaso- 
line supply  at  the  tank. and  to  remove  the  pipe  coupling 
at  the  float  chamber.  It  is  also  necessary  to  disconnect 
the  throttle  operating  rod.  After  the  cylinders  are  re- 
moved and  before  taking  the  crank-case  apart  it  is  well 
to  remove  the  water  pump  and  magneto.  The  wiring  on 
most  engines  of  modern  development  is  carried  in  con- 
duits and  usually  releasing  two  or  three  minor  fastenings 
will  permit  one  to  take  off  the  plug  wiring  as  a  unit. 
The  wire  should  be  disconnected  from  both  spark-plugs 
and  magneto  distributor  before  its  removal.  When  the 
cylinders  are  removed,  the  pistons,  piston  rings,  and  con- 
necting rods  are  clearly  exposed  and  their  condition  may 
be  readily  noticed. 


416  Aviation  Engines 

Before  disturbing  the  arrangement  of  the  timing 
gears,  it  is  important  that  these  be  marked  so  that  they 
will  be  replaced  in  exactly  the  same  relation  as  intended 
by  the  engine  designer.  If  the  gears  are  properly  marked 
the  valve  timing  and  magneto  setting  will  be  undisturbed 
when  the  parts  are  replaced  after  overhauling.  With  the 
cylinders  off,  it  is  possible  to  ascertain  if  there  is  any 
undue  wear  present  in  the  connecting  rod  bearings  at 
either  the  wrist  pin  or  crank-pin  ends  and  also  to  form 
some  idea  of  the  amount  of  carbon  deposits  on  the  piston 
top  and  back  of  the  piston  rings.  Any  wear  of  the  tim- 
ing gears  can  also  be  determined.  The  removal  of  the 
bottom  plate  of  the  engine  enables  the  repairman  to  see 
if  the  main  bearings  are  worn  unduly.  Often  bearings 
may  be  taken  up  sufficiently  to  eliminate  all  looseness.  In 
other  cases  they  may  be  worn  enough  so  that  careful 
refitting  will  be  necessary.  Where  the  crank-case  is 
divided  horizontally  into  two  portions,  the  upper  one 
serving  as  an  engine  base  to  which  the  cylinders  and  in 
fact  all  important  working  parts  are  attached,  the  lower 
portion  performs  the  functions  of  an  oil  container  and 
cover  for  the  internal  mechanism.  This  is  the  construc- 
tion generally  followed. 

DEFECTS   IN    CYLINDERS 

After  the  cylinders  have  been  removed  and  stripped 
of  all  fittings,  they  should  be  thoroughly  cleaned  and  then 
carefully  examined  for  defects.  The  interior  or  bore 
should  be  looked  at  with  a  view  of  finding  score  marks, 
grooves,  cuts  or  scratches  in  the  interior,  because  there 
are  many  faults  that  may  be  ascribed  to  depreciation  at 
this  point.  The  cylinder  bore  may  be  worn  out  of  round, 
which  can  only  be  determined  by  measuring  with  an  in- 
ternal caliper  or  dial  indicator  even  if  the  cylinder  bore 
shows  no  sign  of.  wear.  The  flange  at  the  bottom  of  the 
cylinder  by  which  it  is  held  to  the  engine  base  may  be 
cracked.  The  water  jacket  wall  may  have  opened  up  due 


Defects  in  Cylinders  417 

to  freezing  of  the  jacket  water  at  some  time  or  other  or  it 
may  be  filled  with  scale  and  sediment  due  to  the  use  of 
impure  cooling  water.  The  valve  seat  may  be  scored  or 
pitted,  while  the  threads  holding  the  valve  chamber  cap 
may  be  worn  so  that  the  cap  will  not  be  a  tight  fit.  The 
detachable  head  construction  makes  it  possible  to  remove 
that  member  and  obtain  ready  access  to  the  piston  tops 
for  scraping  out  carbon  without  taking  the  main  cylinder 
portion  from  the  crank-case.  When  the  valves  need  grind- 
ing the  head  may  be  removed  and  carried  to  the  bench 
where  the  work  may  be  performed  with  absolute  assurance 
that  none  of  the  valve  grinding  compound  will  penetrate 
into  the  interior  of  the  cylinder  as  is  sometimes  unavoid- 
able with  the  I-head  cylinder.  If  the  cylinder  should  be 
scored,  the  water  jacket  and  combustion  head  may  be 
saved  and  a  new  cylinder  casting  purchased  at  consider- 
ably less  cost  than  that  of  the  complete  unit  cylinder. 

The  detachable  head  construction  has  only  recently 
been  applied  on  airplane  engines,  though  it  was  one  of 
the  earliest  forms  of  automobile  engine  construction.  In 
the  early  days  it  was  difficult  to  procure  gaskets  or  pack- 
ings that  would  be  both  gas  and  water  tight.  The  sheet 
asbestos  commonly  used  was  too  soft  and  blew  out  read- 
ily. Besides  a  new  gasket  had  to  be  made  every  time 
the  cylinder  head  was  removed.  Woven  wire  and  asbestos 
packings  impregnated  with  rubber,  red  lead,  graphite  and 
other  filling  materials  were  more  satisfactory  than  the 
soft  sheet  asbestos,  but  were  prone  to  burn  out  if  the 
water  supply  became  low.  Materials  such  as  sheet  copper 
or  brass  proved  to  be  too  hard  to  form  a  sufficiently  yield-- 
ing packing  medium  that  would  allow  for  the  inevitable 
slight  inaccuracies  in  machining  the  cylinder  head  and 
cylinder.  The  invention  of  the  copper-asbestos  gasket, 
which  is  composed  of  two  sheets  of  very  thin,  soft  copper 
bound  together  by  a  thin  edging  of  the  same  material 
and  having  a  piece  of  sheet  asbestos  interposed  solved 
this  problem.  Copper-asbestos  packings  form  an  effec- 
tive seal  against  leakage  of  water  and  a  positive  reten- 


418  Aviation  Engines 

tion  means  for  keeping  the  explosion  pressure  in  the 
cylinder.  The  great  advantage  of  the  detachable  head  is 
that  it  permits  of  very  easy  inspection  of  the  piston  tops 
and  combustion  chamber  and  ready  removal  of  carbon 
deposits. 

CARBON   DEPOSITS,    THEIR    CAUSE    AND   PREVENTION 

Most  authorities  agree  that  carbon  is  the  result  of 
imperfect  combustion  of  the  fuel  and  air  mixture  as  well 
as  the  use  of  lubricating  oils  of  improper  flash  point. 
Lubricating  oils  that  work  by  the  piston  rings  may  be- 
come decomposed  by  the  great  heat  in  the  combustion 
chamber,  but  at  the  same  time  one  cannot  blame  the  lubri- 
cating oil  for  all  of  the  carbon  deposits.  There  is  little 
reason  to  suspect  that  pure  petroleum  oil  of  proper  body 
will  deposit  excessive  amounts  of  carbon,  though  if  the 
oil  is  mixed  with  castor  oil,  which  is  of  vegetable  origin, 
there  would  be  much  carbon  left  in  the  interior  of  the 
combustion  chamber.  Fuel  mixtures  that  are  too  rich  in 
gasoline  also  produce  these  undesirable  accumulations. 

A  very  interesting  chemical  analysis  of  a  sample  of 
carbon  scraped  from  the  interior  of  a  motor  vehicle  en- 
gine shows  that  ordinarily  the  lubricant  is  not  as  much 
to  blame  as  is  commonly  supposed.  The  analysis  was 
as  follows: 

Oil    14.3% 

Other  combustible  matter 17.9 

Sand,  clay,  etc 24.8 

Iron  oxide 24.5 

Carbonate  of  lime .        8.9 

Other  constituents , 9.6 

It  is  extremely  probable  that  the  above  could  be  di- 
vided into  two  general  classes,  these  being  approximately 
32.2%  oil  and  'combustible  matter  and  a  much  larger 
proportion,  or  67.8%  of  earthy  matter.  The  presence  of 
such  a  large  percentage  of  earthy  matter  is  undoubtedly 
due  to  the  impurities  in  the  air,  such  as  road  dust  which 


Removal  of  Carbon  Deposits  419 

has  been  sucked  in  through  the  carburetor.  The  fact  that 
over  17-%  of  the  matter  which  is  combustible  was  not  of 
an  oily  nature  lends  strong  support  to  this  view.  There 
would  not  be  the  amount  of  earthy  material  present  in 
the  carbon  deposits  of  an  airplane  engine  as  above  stated 
because  the  air  is  almost  free  from  dust  at  the  high  alti- 
tudes planes  are  usually  flown.  One  could  expect  to  find 
more  combustible  and  less  earthy  matter  and  the  carbon 
would  be  softer  and  more  easily  removed.  It  is  very  good 
practice  to  provide  a  screen  on  the  air  intake  to  reduce 
the  amounts  of  dust  sucked  in  with  the  air  as  well  as 
observing  the  proper  precautions  relative  to  supplying 
the  proper  quantities  of  air  to  the  mixture  and  of  not 
using  any  more  oil  than  is  needed  to  insure  proper  lubri- 
cation of  the  internal  mechanism. 


USE   OF    CARBON   SCRAPERS 

It  is  not  unusual  for  one  to  hear  an  aviator  complain 
that  the  engine  he  operates  is  not  as  responsive  as  it  was 
when  new  after  he  has  run  it  but  relatively  few  hours. 
There  does  not  seem  to  be  anything  actually  wrong  with 
the  engine,  yet  it  does  not  respond  readily  to  the  throttle 
and  is  apt  to  overheat.  While  these  symptoms  denote  a 
rundown  condition  of  the  mechanism,  the  trouble  is  often 
due  to  nothing  more  serious  than  accumulations  of  car- 
bon. The  remedy  is  the  removal  of  this  matter  out  of 
place.  The  surest  way  of  cleaning  the  inside  of  the  motor 
thoroughly  is  to  remove  the  cylinders,  if  these  members 
are  cast  integrally  with  the  head  or  of  removing  the  head 
member  if  'that  is  a  separate  casting,  to  expose  all  parts. 

In  certain  forms  of  cylinders,  especially  those  of  the 
L  form,  it  is  possible  to  introduce  simple  scrapers  down 
through  the  valve  chamber  cap  holes  and  through  the 
spark-plug  hole  if  this  component  is  placed  in  the  cylin- 
der in  some  position  that  communicates  directly  to  the 
interior  of  the  cylinder  or  to  the  piston  top.  No  claim 
can  be  made  for  originality  or  novelty  of  this  process  as 


420  Aviation  Engines 

is  has  been  used  for  many  years  on  large  stationary  en- 
gines. The  first  step  is  to  dismantle  the  inlet  and  ex- 
haust piping  and  remove  the  valve  caps  and  valves,  al- 
though if  the  deposit  is  not  extremely  hard  or  present 
in  large  quantities  one  can  often  manipulate  the  scrapers 
in  the  valve  cap  openings  without  removing  either  the 
piping  or  the  valves.  Commencing  with  the  first  cylinder, 
the  crank-shaft  is  turned  till  the  piston  is  at  the  top  of 
its  stroke,  then  the  scraper  may  be  inserted,  and  the 
operation  of  removing  the  carbon  started  by  drawing  the 
tool  toward  the  opening.  As  this  is  similar  to  a  small 
hoe,  the  cutting  edge  will  loosen  some  of  the  carbon  and 
will  draw  it  toward  the  opening.  A  swab  is  made  of  a 
piece  of  cloth  or  waste  fastened  at  the  end  of  a  wire  and 
well  soaked  in  kerosene  to  clean  out  the  cylinder. 

When  available,  an  electric  motor  with  a  length  of 
flexible  shaft  and  a  small  circular  cleaning  brush  having 
wire  bristles  can  be  used  in  the  interior  of  the  engine. 
The  electric  motor  need  not  be  over  one-eighth  horse- 
power running  1,200  to  1,600  E.  P.  M.,  and  the  wire  brush 
must,  of  course,  be  of  such  size  that  it  can  be  easily  in* 
serted  through  the  valve  chamber  cap.  The  flexible  shaft 
permits  one  to  reach  nearly  all  parts  of  the  cylinder  in- 
terior without  difficulty  and  the  spreading  out  and  flatten- 
ing of  the  brush  insures  that  considerable  surface  will  be 
covered  by  that  member. 

BURNING   OUT    CARBON    WITH    OXYGEN 

A  process  of  recent  development  that  gives  very  good 
results  in  removing  carbon  without  disassembling  the 
motor  depends  on  the  process  of  burning  out  that  ma- 
terial by  supplying  oxygen  to  support  the  combustion 
and  to  make  it  energetic.  A  number  of  concerns  are  al- 
ready offering  apparatus  to  accomplish  this  work,  and  in 
fact  any  shop  using  an  autogenous  welding  outfit  may 
use  the  oxygen  tank  and  reducing  valve  in  connection 
with  a  simple  special  torch  for  burning  the  carbon.  Ke- 


Carbon  Removal 


421 


suits  have  demonstrated  that  there  is  little  danger  of 
damaging  the  motor  parts,  and  that  the  cost  of  oxygen 
and  labor  is  much  lower  than  the  old  method  of  removing 
the  cylinders  and  scraping  the  carbon  out,  as  well  as 
being  very  much  quicker  than  the  alternative  process  of 
using  carbon  solvent.  The  only  drawback  to  this  system 
is  that  there  is  no  absolute  insurance  that  every  particle 
of  carbon  will  be  removed,  as  small  protruding  particles 
may  be  left  at*  points  that  the  flame  does  not  reach  and 


•Trigger  Valve 

G 

,'Ma'm 
Valve 


Where  Carbon  Deposits 
collect  in  Combust/on  Head 


Hose- 


Pressure 
Regulator 


Fig.  182. — Showing  Where  Carbon  Deposits  Collect  in  Engine  Combustion 
Chamber,  and  How  to  Burn  Them  Out  with  the  Aid  of  Oxygen.  A — 
Special  Torch.  B — Torch  Coupled  to  Oxygen  Tank.  C — Torch  in  Use. 

cause  pre-ignition  and  consequent  pounding,  even  after 
the. oxygen  treatment.  It  is  generally  known  that  carbon 
will  burn  in  the  presence  of  oxygen,  which  supports  com- 
bustion of  all  materials,  and  this  process  takes  advantage 
of  this  fact  and  causes  the  gas  to  be  injected  into  the 
combustion  chamber  over  a  flame  obtained  by  a  match  or 
wax  taper. 

li  is  suggested  by  those  favoring  this  process  that 
the  night  before  the  oxygen  is  to  be  used  the  engine  be 
given  a  conventional  kerosene  treatment.  A  half  tumbler 
full  of  this  liquid  or  of  denatured  alcohol  is  to  be  poured 


422  Aviation  Engines 

into  each  cylinder  and  permitted  to  remain  there  over 
night.  As  a  precaution  against  fire,  the  gasoline  is  shut 
off  from  the  carburetor  before  the  torch  is  inserted  in 
the  cylinder  and  the  motor  started  so  that  the  gasoline  in 
the  pipe  and  carburetor  float  chamber  will  be  consumed. 
Work  is  done  on  one  cylinder  at  a  time.  A  note  of  cau- 
tion was  recently  sounded  by  a  prominent  spark-plug 
manufacturer  recommending  that  the  igniter  member  be 
removed  from  the  cylinder  in  order  not  to  injure  it  by 
the  heat  developed.  The  outfits  on  the  market  consist 
of  a  special  torch  having  a  trigger  controlled  valve  and 
a  length  of  flexible  tubing  such  as  shown  at  Fig.  182,  A, 
and  a  regulating  valve  and  oxygen  tank  as  shown  at  B. 
The  gauge  should  be  made  to  register  about  twelve 
pounds  pressure. 

The  method  of  operation  is  very  simple  and  is  out- 
lined at  C.  The  burner  tube  is  placed  in  the  cylinder  and 
the  trigger  valve  is  opened  and  the  oxygen  permitted  to 
circulate  in  the  combustion  chamber.  A  lighted  match 
or  wax  taper  is  dropped  in  the  chamber  and  the  injector 
tube  is  moved  around  as  much  as  possible  so  as  to  cover 
a  large  area.  The  carbon  takes  fire  and  burns  briskly  in 
the  presence  of  the  oxygen.  The  combustion  of  the  car- 
bon is  accompanied  by  sparks  and  sometimes  by  flame  if 
the  deposit  is  of  an  oily  nature.  Once  the  carbon  begins 
to  burn  the  combustion  continues  without  interruption  as 
long  as  the  oxygen  flows  into  the  cylinder.  Full  instruc- 
tions accompany  each  outfit  and  the  amount  of  pressure 
for  which  the  regulator  should  be  set  depends  upon 'the 
design  of  the  torch  and  the  amount  of  oxygen  contained 
in  the  storage  tank. 

REPAIRING    SCORED    CYLINDERS 

If  the  engine  has  been  run  at  any  time  without  ade- 
quate lubrication,  one  or  more  of  the  cylinders  may  be 
found  to  have  vertical  scratches  running  up  and  down 
the  cylinder  walls.  The  depth  of  these  will  vary  accord- 


Repairing  Scored  Cylinders  423 

ing  to  the  amount  of  time  the  cylinder  was  without  lubri- 
cation, and  if  the  grooves  are  very  deep  the  only  remedy 
is  to  purchase  a  new  member.  Of  course,  if  sufficient 
stock  is  available  in  the  cylinder  walls,  the  cylinders  may 
be  rebored  and  new  pistons  which  are  oversize,  i.e.,  larger 
than  standard,  may  be  fitted.  Where  the  scratches  are 
not  deep  they  may  be  ground  out  with  a  high  speed  emery 
wheel  or  lapped  out  if  that  type  of  machine  is  not  avail- 
able. Wrist  pins  have  been  known  to  come  loose,  espe- 
cially when  these  are  retained  by  set  screws  that  are  not 
properly  locked,  and  as  wrist-pins  are  usually  of  hard- 
ened steel  it  will  be  evident  that  the  sharp  edge  of  that 
member  can  act  as  a  cutting  tool  and  make  a  pronounced 
groove  in  the  cylinder.  Cylinder  grinding  is  a  job  that 
Requires  skilled  mechanics,  but  may  be  accomplished  on 
any  lathe  fitted  with  an  internal  grinding  attachment. 
While  automobile  engine  cylinders  usually  have  sufficient 
wall  thickness  to  stand  reboring,  those  of  airplane  engines 
seldom  have  sufficient  metal  to  permit  of  enlarging  the 
bore  very  much  by  a  boring  tool.  A  few  thousandths  of 
an  inch  may  be  ground  out  without  danger,  however. 
An  airplane  engine  cylinder  with  deep  grooves  must  be 
scrapped  as  a  general  rule. 

Where  the  grooves  in  the  cylinder  are  not  deep  or 
where  it  has  warped  enough  so  the  rings  do  not  bear 
equally  at  all  parts  of  the  cylinder  bore,  it  is  possible  to 
obtain  a  fairly  accurate  degree  of  finish  by  a  lapping  pro- 
cess in  which  an  old  piston  is  coated  with  a  mixture  of 
fine  emery  and  oil  and  is  reciprocated  up  and  down  in  the 
cylinder  as  well  as  turned  at  the  same  time.  This  may 
be  easily  done  by  using  a  dummy  connecting  rod  having 
only  a  wrist  pin  end  boss,  and  of  such  size  at  the  other 
end  so  that  it  can  be  held  in  the  chuck  of  a  drill  press. 
The  cylinder  casting  is  firmly  clamped  on  the  drill  press 
table  by  suitable  clamping  blocks,  and  a  wooden  block  is 
placed  in  the  combustion  chamber  to  provide  a  stop  for 
the  piston  at  its  lower  extreme  position.  The  back  gears 
are  put  in  and  the  drill  chuck  is  revolved  slowly.  All  the 


424  Aviation  Engines 

while  that  the  piston  is  turning  the  drill  chuck  should  be 
raised  up  and  down  by  the  hand  feed  lever,  as  the  best 
results  are  obtained  when  the  lapping  member  -is  given 
a  combination  of  rotary  and  reciprocating  motion. 


VALVE*  REMOVAL,   AND    INSPECTION 

One  of  the  most  important  parts  of  the  gasoline  en- 
gine and  one  that  requires  frequent  inspection  and  refit- 
ting to  keep  in  condition,  is  the  mushroom  or  poppet  valve 
that  controls  the  inlet  and  exhaust  gas  flow.  In  over- 
hauling it  is  essential  that  these  valves  be  removed  from 
their  seatings  and  examined  carefully  for  various  defects 
which  will  be  enumerated  at  proper  time.  The  problem 
that  concerns  us  now  is  the  best  method  of  removing  the- 
valve.  These  are  held  against  the  seating  in  the  cylinder 
by  a  coil  spring  which  exerts  its  pressure  on  the  cylinder 
casting  at  the  upper  end  and  against  a  suitable  collar 
held  by  a  key  at  the  lower  end  of  the  valve  stem.  In 
order  to  remove  the  valve  it  is  necessary  to  first  com- 
press the  spring  by  raising  the  collar  -and  pulling  the 
retaining  key  out  of  the  valve  stem.  Many  forms  of  valve 
spring  lifters  have  been  designed  to  permit  ready  re- 
moval of  the  valves. 

When  the  cylinder  is  of  the  valve  in-the-head  form, 
the  method  of  valve  removal  will  depend  entirely  upon 
the  system  of  cylinder  construction  followed.  In  the 
Sturtevant  cylinder  design  it  is  possible  to  remove  the 
head  from  the  cylinder  castings  and  the  valve  springs 
may  be  easily  compressed  by  any  suitable  means  when 
the  cylinder  head  is  placed  on  the  work  bench  where  it 
can  be  easily  worked  on.  The  usual  method  is  to  place 
the  head  on  a  soft  cloth  with  the  valves  bearing  against 
the  bench.  The  valve  springs  may  then  be  easily  pushed 
down  with  a  simple  forked  lever  and  the  valve  stem  key 
removed  to  release  the  valve  spring  collar.  In  the  Curtiss 
OX-2  (see  Fig.  182%)  and  Hall-Scott  engines  it  is  not 
possible  to  remove  the  valves  without  taking  the  cylinder 


Valve  Removal  and  Inspection 


425 


off  the  crank-case,  because  the  valve  seats  are  machined 
directly  in  the  cylinder  head  and  the  valve  domes  are  cast 
integrally  with  the  cylinder.  This  means  that  if  the  valves 
need  grinding  the  cylinder  must  be  removed  from  the 
engine  base  to  provide  access  to  the  valve  heads  which 
are  inside  of  that  member,  and  which  cannot  be  reached 


fnlet.  Valve 
Spring  - 

/n/ef  Port 


Water 
Outlet 


Water  .Space 


Exhaust 

Valve  Spring 


Cylinder — ^ 


pplied  Wafer 
•    '  Jacket 


Cylinder 


m*~Cool  Water 
P"      Jn  let 


Base 

Flange 


Fig.  182y2. — Part  Sectional  View,  Showing  Valve  Arrangement  in  Cylinder 
of  Curtiss  OX-2  Aviation  Engine. 

from  the  outside  as  is  true  of  the  L-cylinder  construction. 
In  the  Curtiss  VX  engines,  the  valves  are  carried  in  de- 
tachable cages  which  may  be  removed  when  the  valves 
need  attention. 


RESEATING  AND  TRUING  VALVES 

Much  has  been  said  relative  to  valve  grinding,  and 
despite  the  mass  of  information  given  in  the  trade  prints 


426  Aviation  Engines 

it  is  rather  amusing  to  watch  the  average  repairman  or  the 
engine  user  who  prides  himself  on  maintaining  his  own 
motor  performing  this  essential  operation.  The  common 
mistakes  are  attempting  to  seat  a  badly  grooved  or  pitted 
valve  head  on  an  equally  bad  seat,  which  is  an  almost 
hopeless  job,  and  of  using  coarse  emery  and  bearing  down 
with  all  one's  weight  on  the  grinding  tool  with  the  hope 
of  quickly  wearing  away  the  rough  surfaces.  The  use  of 
improper  abrasive  material  is  a  fertile  cause  of  failure 
to  obtain  a  satisfactory  seating.  Valve  grinding  is  not  a 
difficult  operation  if  certain  precautions  are  taken  before 
undertaking  the  work.  The  most  important  of  these  is 
to  ascertain  if  the  valve  head  or  seat  is  badly  scored  or 
pitted.  If  such  is  found  to  be  the  case  no  ordinary 
amount  of  grinding  will  serve  to  restore  the  surfaces.  In 
this  event  the  best  thing  to  do  is  to  remove  the  valve 
from  its  seating  and  to  smooth  down  both  the  valve  head 
and  the  seat  in  the  cylinder  before  attempt  is  made  to 
fit  them  together  by  grinding.  Another  important  pre- 
caution is  to  make  sure  that  the  valve  stem  is  straight, 
and  that  the  head  is  not  warped  out  of  shape. 

A  number  of  simple  tools  is  available  at  the  present 
time  for  reseating  valves,  these  being  outlined  at  Fig. 
183.  That  shown  at  A  is  a  simple  fixture  for  facing  off 
the  valve  head.  The  stem  is  supported  by  suitable  bear- 
ings carried  by  the  body  or  shank  of  the  tool,  and  the 
head  is  turned  against  an  angularly  disposed  cutter  which 
is  set  for  the  proper  valve  seat  angle.  The  valve  head 
is  turned  by  a  screw-driver,  the  amount  of  stock  removed 
from  the  head  depending  upon  the  location  of  the  adjust- 
ing screw.  Care  must  be  taken  not  to  remove  too  much 
metal,  only  enough  being  taken  off  to  remove  the  most 
of  the  roughness.  Valves  are  made  in  two  standard 
tapers,  the  angle  being  either  45  or  60  degrees.  It  is  im- 
perative that  the  cutter  blade  be  set  correctly  in  order 
that  the  bevel  is  not  changed.  A  set  of  valve  truing  and 
valve-seat  reaming  cutters  is  shown  at  Fig.  183,  B.  This 
is  adaptable  to  various  size  valve  heads,  as  the  cutter 


Valve  Restoration 


42? 


blade  D  may  be  moved  to  correspond  to  the  size  of  the 
valve  head  being  trued  up.    These  cutter  blades  are  made 


£ooy 


Fig.  183. — Tools  for  Restoring  Valve  Head  and  Seats. 

of  tool  steel  and  have  a  bevel  at  each  end,  one  at  45  de- 
grees, the  other  at  60  degrees.  The  valve  seat  reamer 
shown  at  G  will  take  any  one  of  the  heads  shown  at  F. 


428  Aviation  Engines 

It  will  also  take  any  one  of  the  guide  bars  shown  at  H. 
The  function  of  the  guide  bars  is  to  fit  the  valve  stem 
bearing  in  order  to  locate  the  reamer  accurately  and  to 
insure  that  the  valve  seat  is  machined  concentrically  with 
its  normal  center.  Another  form  of  valve  seat  reamer 
and  a  special  wrench  used  to  turn  it  is  shown  at  C.  The 
valve  head  truer  shown  at  Fig.  183,  D,  is  intended  to  be 
placed  in  a  vise  and  is  adaptable  to  a  variety  of  valve 
head  sizes.  The  smaller  valves  merely  fit  deeper  in  the 
conical  depression.  The  cutter  blade  is  adjustable  and 
the  valve  stem  is  supported  by  a  simple  self-centering 
bearing.  In  operation  it  is  intended  that  the  valve  steni, 
which  protrudes  through  the  lower  portion  of  the  guide 
bearing,  shall  be  turned  by  a  drill  press  or  bit  stock  while 
the  valve  head  is  set  against  the  cutter  by  pressure  of  a 
pad  carried  at  the  end  of  a  feed  screw  which  is  supported 
by  a  hinged  bridge  member.  This  can  be  swung  out  of 
place  as  indicated  to  permit  placing  the  valve  head  against 
the  cutter  .or  removing  it. 

As  the  sizes  of  valve  heads  and  stems  vary  consider- 
ably a  "Universal"  valve  head  truing  tool  must  have 
some  simple  means  of  centering  the  valve  stem  in  order 
to  insure  concentric  machining  of  the  valve  head.  A  valve 
head  truer  which  employs  an  ingenious  method  of  guid- 
ing the  valve  stem  is  shown  at  Fig.  183,  E.  The  device 
consists  of  a  body  portion,  B,  provided  with  an  external 
thread  at  the  top  on  which  the  cutter  head,  A,  is  screwed. 
A  number  of  steel  balls,  C,  are  carried  in  the  grooves 
which  may  be  altered  in  size  by  the  adjustment  nut,  F, 
which  screws  in  the  bottom  of  the  body  portion,  B.  As 
the  nut  F  is  screwed  in  against  the .  spacer  member  E, 
the  V-grooves  are  reduced  in  size  and  the  steel  balls,  C, 
are  pressed  out  in  contact  with  the  valve  stem.  As  the 
circle  or  annulus  is  filled  with  balls  in  both  upper  and 
lower  portions  the  stem  may  be  readily  turned  because 
it  is  virtually  supported  by  ball  bearing  guides.  When 
a  larger  valve  stem  is  to  be  supported,  the  adjusting  nut 
F,  is  screwed  out  which  increases  the  size  of  the  grooves 


Valve  Grinding  Processes  429 

and  permits  the  balls,  C,  to  spread  out  and  allow  the  larger 
stem  to  be  inserted. 


VALVE    GRINDING   PROCESSES 

Mention  has  been  previously  made  of  the  importance 
of  truing  both  valve  head  and  seat  before  attempt  is  made 
to  refit  the  parts  by  grinding.  After  smoothing  the  valve 
seat  the  next  step  is  to  find  some  way  of  turning  the  valve. 
Valve  heads  are  usually  provided  with  a  screw-driver  slot 
passing  through  the  boss  at  the  top  of  the  valve  or  with 
two  drilled  holes  to  take  a  forked  grinding  tool.  A  com- 
bination grinding  tool  has  been  devised  which  may  be 
used  when  either  the  two  drilled  holes  or  the  slotted  head 
form  of  valve  is  to  be  rotated.  This  consists  of  a  special 
form  of  screw  driver  having  an  enlarged  boss  just  above 
the  blade,  this  boss  serving  to  support  a  U-shape  piece 
which  can  be  securely  held  in  operative  position  by  the 
clamp  screw  or  which  can  be  turned  out  of  the  way  if 
the  screw  driver  blade  is  to  be  used. 

As  it  is  desirable  to  turn  the  valve  through  a  portion 
of  a  revolution  and  back  again  rather  than  turning  it 
always  in  the  same  direction,  a  number  of  special  tools 
has  been  designed  to  make  this  oscillating  motion  possible 
without  trouble.  A  simple  valve  grinding  tool  is  shown 
at  Fig.  184,  C.  This  consists  of  a  screw-driver  blade 
mounted  in  a  handle  in  such  a  way  that  the  end  may 
turn  freely  in  the  handle.  A  pinion  is  securely  fastened 
to  the  screw-driver  blade  shank,  and  is  adapted  to  fit  a 
race  provided  with  a  wood  handle  and  guided  by  a  bent 
bearing  member  securely  fastened  to  the  screw-driver 
handle.  As  the  rack  is  pushed  back  and  forth  the  pinion 
must  be  turned  first  in  one  direction  and  then  in  the  other. 

A  valve  grinding  tool  patterned  largely  after  a  breast 
drill  is  shown  at  Fig.  184,  D.  This  is  worked  in  such  a 
manner  that  a  continuous  rotation  of  the  operating  crank 
will  result  in  an  oscillating  movement  of  the  chuck  carry- 
ing the  screw-driver  blade.  The  bevel  pinions  which  are 


1.30 


Aviation  Engines 


used  to  turn  the  chuck  are  normally  free  unless  clutched 
to  the  chuck  stem  by  the  sliding  sleeve  which  must  turn 
with  the  chuck  stem  and  which  carries  clutching  members 


•Valve 


-Valve  Cage 

—  Va/ve  Stem 
•-•Na/f 


'•Valve  Stem 


Fig.  184. — Tools  and  Processes  Utilized  in  Valve   Grinding. 

at  each  end  to  engage  similar  members  on  the  bevel  pin- 
ions and  lock  these  to  the  chuck  stem,  one  at  a  time.  The 
bevel  gear  carries  a  cam-piece  which  moves  the  clutch 


Valve  Grinding  Processes  431 

sleeve  back  and  forth  as  it  revolves.  This  means  that  the 
pinion  giving  forward  motion  of  the  chuck  is  clutched  to 
the  chuck  spindle  for  a  portion  of  a  revolution  of  the 
gear  and  clutch  sleeve  is  moved  back  by  the  cam  and 
clutched  to  the  pinion  giving  a  reverse  motion  of  the 
chuck  during  the  remainder  of  the  main  drive  gear  revo- 
lution. 

It  sometimes  happens  that  the  adjusting  screw  on  the 
valve  lift  plunger  or  the  valve  lift  plunger'  itself  when 
L  head  cylinders  are  used  does  not  permit  the  valve  head 
to  rest  against  the  seat.  It  will  be  apparent  that  unless 
a  definite  space  exists  between  the  end  of  the  valve  stem 
and  the  valve  lift  plunger  that  grinding  will  be  of  little 
avail  because  the  valve  head  will  not  bear  properly 
against  the  abrasive  material  smeared  on  the  valve  seat. 

The  usual  methods  of  valve  grinding  are  clearly  out- 
lined at  Fig.  184.  The  view  at  the  left  shows  the  method 
of  turning  the  valve  by  an  ordinary  screw  driver  and  also 
shows  a  valve  head  at  A,  having  both  the  drilled  holes 
and  the  screw-driver  slot  for  turning  the  member  and  two 
special  forms  of  fork-end  valve  grinding  tools.  In  the 
sectional  view  shown  at  the  right,  the  use  of  the  light 
spring  between  the  valve  head  and  the  bottom  of  the  valve 
chamber  to  lift  the  valve  head  from  the  seat  whenever 
pressure  on  the  grinding  tool  is  released  is  clearly  indi- 
cated. It  will  be  noted  also  that  a  ball  of  waste  or  cloth 
is  interposed  in  the  passage  between  the  valve  chamber 
and  the  cylinder  interior  to  prevent  the  abrasive  material 
from  passing  into  the  cylinder  from  the  valve  chamber. 
When  a  bitstock  is  used,  instead  of  being  given  a  true 
rotary  motion  the  chuck  is  merely  oscillated  through  the 
greater  part  of  the  circle  and  back  again.  It  is  necessary 
to  lift  the  valve  from  its  seat  frequently  as  the  grinding 
operation  continues;  this  is  to  provide  an  even  distribu- 
tion of  the  abrasive  material  placed  between  the  valve 
head  and  its  seat.  Only  sufficient  pressure  is  given  to 
the  bitstock  to  overcome  the  uplift  of  the  spring  and  to 
insure  that  the  valve  will  be  held  against  the  seat.  Where 


432  Aviation  Engines 

the  spring  is  not  used  it  is  possible  to  raise  the  valve 
from  time  to  time  with  the  hand  which  is  placed  under 
the  valve  stem  to  raise  it  as  the  grinding  is  carried  on. 
It  is  not  always  possible  to  lift  the  valve  in  this  manner 
when  the  cylinders  are  in  place  on  the  engine  base  owing 
to  the  space  between  the  valve  lift  plunger  and  the  end 
of  the  valve  stem.  In  this  event  the  use  of  the  spring  as 
shown  in  sectional  view  will  be  desirable. 

The  abrasive  generally  used  is  a  paste  made  of 
medium  or  fine  emery  and  lard  oil  or  kerosene.  This  is 
used  until  the  surfaces  are  comparatively  smooth,  after 
which  the  final  polish  or  finish  is  given  with  a  paste  of 
flour  emery,  grindstone  dust,  crocus,  or  ground  glass  and 
oil.  An  erroneous  impression  prevails  in  some  quarters 
that  the  valve  head  surface  and  the  seating  must  have 
a  mirror-like  polish.  While  this  is  not  necessary  it  is 
essential  that  the  seat  in  the  cylinder  and  the  bevel  sur- 
face of  the  head  be  smooth  and  free  from  pits  or  scratches 
at  the  completion  of  the  operation.  All  traces  of  the 
emery  and  oil  should  be  thoroughly  washed  out  of  the 
valve  chamber  with  gasoline  before  the  valve  mechanism 
is  assembled  and  in  fact  it  is  advisable  to  remove  the  old 
grinding  compound  at  regular  intervals,  wash  the  seat 
thoroughly  and  supply  fresh  material  as  the  process  is  in 
progress. 

The  truth  of  seatings  may  be  tested  by  taking  some 
Prussian  blue  pigment  and  spreading  a  thin  film  of  it 
over  the  valve  seat.  The  valve  is  dropped  in  place  and 
is  given  about  one-eighth  turn  with  a  little  pressure  on 
the  tool.  If  the  seating  is  good  both  valve  head  and  seat 
will  be  covered  uniformly  with  color.  If  high  spots  exist, 
the  heavy  deposit  of  color  will  show  these  while  the  low 
spots  will  be  made  evident  because  of  the  lack  of  pig- 
ment. The  grinding  process  should  be  continued  until 
the  test  shows  an  even  bearing  of  the  valve  head  at  all 
points  of  the  cylinder  seating.  When  the  valves  are  held 
in  cages  it  is  possible  to  catch  the  cage  in  a  vise  and  to 
turn  the  valve  in  any  of  the  ways  indicated.  It  is  much 


Depreciation  In  Valve  Systems  433 

easier  to  clean  off  the  emery  and  oil  and  there  is  abso- 
lutely no  danger  of  getting  the  abrasive  material  in  the 
cylinder  if  the  construction  is  such  that  the  valve  cage 
or  cylinder  head  member  carrying  the  valve  can  be  re- 
moved from  the  cylinder.  When  valves  are  held  in  cages, 
the  tightness  of  the  seat  may  be  tested  by  partially  filling 
the  cage  with  gasoline  and  noticing  how  much  liquid  oozes 
out  around  the  valve  head.  The  degree  of  moisture  pres- 
ent indicates  the  efficacy  of  the  grinding  process. 

The  valves  of  Curtiss  OX-2  cylinders  are  easily 
ground  in  by  using  a  simple  fixture  or  tool  and  working 
from  the  top  of  the  cylinder  instead  of  from  the  inside. 
A  tube  having  a  bore  just  large  enough  to  go  over  the 
valve  stem  is  provided  with  a  wooden  handle  or  taped  at 
one  end  and  a  hole  of  the  same  size  as  that  drilled  through 
the  valve  stem  is  put  in  at  the  other.  To  use,  the  open 
end  of  the  tube  is  pushed  over  the  valve  stem  and  a  split 
pin  pushed  through  the  tube  and  stem.  The  valve  may 
be  easily  manipulated  and  ground  in  place  by  oscillating 
in  the  customary  manner. 


DEPRECIATION-    IN    VALVE    OPERATING    SYSTEMS 

There  are  a  number  of  points  to  be  watched  in  the 
valve  operating  system  because  valve  timing  may  be  seri- 
ously interfered  with  if  there  is  much  lost  motion  at  the 
various  bearing  points  in  the  valve  lift  mechanism.  The 
two  conventional  methods  of  opening  valves  are  shown  at 
Fig.  185.  That  at  A  is  the  type  employed  when  the  valve 
cages  are  mounted  directly  in  the  head,  while  the  form  at 
B  is  the  system  used  when  the  valves  are  located  in  a 
pocket  or  extension  of  the  cylinder  casting  as  is  the  case 
if  an  L,  or  T-head  cylinder  is  used.  It  will  be  evident 
that  there  are  several  points  where  depreciation  may  take 
place.  The  simplest  form  is  that  shown  at  B,  and  even  on 
this  there  are  five  points  where  lost  motion  may  be  noted. 
The  periphery  of  the  valve  opening  cam  or  roller  may  be 
worn,  though  this  is  not  likely  unless  the  roller  or  cam  has 


434 


Aviation  Engines 


been  inadvertently  left  soft.  The  pin  which  acts  as  a 
bearing  for  the  roller  may  become  worn,  this  occurring 
quite  often.  Looseness  may  materialize  between  the  bear- 
ing surfaces  of  the  valve  lift  plunger  and  the  plunger 


.-Rocker  Lever 


Fulcrum. 


A 

-Tappet  Rod 

,.- Valve  Plunger-'  J|_, 


--,-  Valve  -Plunger 
Guide  ....... 


Valve 


Rocker  firm. 

/  Fulcrum  Pin, 


Valve  Spring^ 

Cage 
Retaining, 
Nut    ' 


Pin. 


—Vafve 
5     Stem 


''Valve  -Operating  Caws- 


Fig.  185. — Outlining  Points  in  Valve  Operating  Mechanism  Where  Depre- 
ciation is  Apt  to  Exist. 

guide  casting,  and  there  may  also  be  excessive  clearance 
between  the  top  of  the  plunger  and  the  valve  stem. 

On  the  form  shown  at  A,  there  are  several  parts  added 
to  those  indicated  at  B.  A  walking  beam  or  rocker  lever 
is  necessary  to  transform  the  upward  motion  of  the  tappet 
rod  to  a  downward  motion  of  the'  valve  stem.  The  pin 


Depreciation  In  Valve  Systems  435 

on  which  this  member  fulcrums  may  wear  as  will  also  the 
other  pin  acting  as  a  hinge  or  bearing  for  the  yoke  end 
of  the  tappet  rod.  It  will  be  apparent  that  if  slight  play 
existed  at  each  of  the  points  mentioned  it  might  result  in 
a  serious  diminution  of  valve  opening.  Suppose,  for  ex- 
ample, that  there  were  .005-inch  lost  motion  at  each  of 
three  bearing  points,  the  total  lost  motion  would  be  .015- 
inch  or  sufficient  to  produce  noisy  action  of  the  valve 
mechanism.  When  valve  plungers  of  the  adjustable  form, 
such  as  shown  at  B,  are  used,  the  hardened  bolt  head  in 
contact  with  the  end  of  the  valve  stem  may  become  hol- 
lowed out  on  account  of  the  hammering  action  at  that 
point.  It  is  imperative  that  the  top  of  this  member  be 
ground  off  true  and  the  clearance  between  the  valve  stem 
and  plunger  properly  adjusted.  If  the  plunger  is  a  non- 
adjustable  type  it  will  be  necessary  to  lengthen  the  valve 
stem  by  some  means  in  order  to  reduce  the  excessive 
clearance.  The  only  remedy  for  wear  at  the  various 
hinges  and  bearing  pins  is  to  bore  the  holes  out  slightly 
larger  and  to  fit  new  hardened  steel  pins  of  larger  diam- 
eter. Depreciation  between  the  valve  plunger  guide  and 
the  valve  plunger  is  usually  remedied  by  fitting  new 
plunger  guides  in  place  of  the  worn  ones.  If  there  is 
sufficient  stock  in  the  plunger  guide  casting  as  is  some- 
times the  case  when  these  members  are  not  separable  from 
the  cylinder  casting,  the  guide  may  be  bored  out  and 
bushed  with  a  light  bronze  bushing. 

A  common  cause  of  irregular  engine  operation  is  due  to 
a  sticking  valve.  This  may  be  owing  to  a  bent  valve  stem, 
a  weak  or  broken  valve  spring  or  an  accumulation  of 
burnt  or  gummed  oil  between  the  valve  stem  and  the 
valve  stem  guide.  In  order  to  prevent  this  the  valve  stem 
must  be  smoothed  with  fine  emery  cloth  and  no  burrs  or 
shoulders  allowed  to  remain  on  it,  and  the  stem  must  also 
be  straight  and  at  right  angles  to  the  valve  head.  If  the 
spring  is  weak  it  may  be  strengthened  in  some  cases  by 
stretching  it  out  after  annealing  so  that  a  larger  space 
will  exist  between  the  coils  and  re-hardening.  Obviously 


436  Aviation  Engines 

if  a  spring  is  broken  the  only  remedy  is  replacement  of 
the  defective  member. 

Mention  has  been  made  of  wear  in  the  valve  stem 
guide  and  its  influence  on  engine  action.  When  these 
members  are  an  integral  part  of  the  cylinder  the  only 
method  of  compensating  for  this  wear  is  to  drill  the  guide 
out  and  fit  a  bushing,  which  may  be  made  of  steel  tube. 

In  some  engines,  especially  those  of  recent  develop- 
ment, the  valve  stem  guide  is  driven  or  screwed  into  the 
cylinder  casting  and  is  a  separate  member  which  may  be 
removed  when  worn  and  replaced  with  a  new  one.  When 
the  guides  become  enlarged  to  such  a  point  that  con- 
siderable play  exists  between  them  and  the  valve  stems, 
they  may  be  easily  knocked  out  or  unscrewed. 

PISTON    TROUBLES 

If  an  engine  has  been  entirely  dismantled  it  is  very 
easy  to  examine  the  pistons  for  deterioration.  While  it 
is  important  that  the  piston  be  a  good  fit  in  the  cylinder 
it  is  mainly  upon  the  piston  rings  that  compression  de- 
pends. The  piston  should  fit  the  cylinder  with  but  little 
looseness,  the  usual  practice  being  to  have  the  piston 
about  .001-inch  smaller  than  the  bore  for  each  inch  of 
piston  diameter  at  the  point  where  the  least  heat  is  pres- 
ent or  at  the  bottom  of  the  piston.  It  is  necessary  to 
allow  more  than  this  at  the  top  of  the  piston  owing  to  its 
expansion  due  to  -the  direct  heat  of  the  explosion.  The 
clearance  is  usually  graduated  and  a  piston  that  would  be 
.005-inch  smaller  than  the  cylinder  bore  at  the  bottom 
would  be  about  .0065-inch  at  the  middle  and  .0075-inch  at 
the  top.  If  much  more  play  than  this  is  evidenced  the 
piston  will  "slap"  in  the  cylinder  and  the  piston  will  be 
worn  at  the  ends  more  than  in  the  center.  Aluminum  or 
alloy  pistons  require  more  clearance  than  cast  iron  ones 
do,  usually  1.50  times  as  much.  Pistons  sometimes  warp 
out  of  shape  and  are  not  truly  cylindrical.  This  results 
in  the  high  spots  rubbing  on  the  cylinder  while  the  low 


Piston  and  Ring  Troubles  437 

spots  will  be  blackened  where  a  certain  amount  of  gas 
has  leaked  by. 

Mention  has  been  previously  made  of  the  necessity  of 
reboring  or  regrinding  a  cylinder  that  has  become  scored 
or  scratched  and  which  allows  the  gas  to  leak  by  the 
piston  rings.  When  the  cylinder  is  ground  out,  it  is  nec- 
essary to  use  a  larger  piston  to  conform  to  the  enlarged 
cylinder  bore.  Most  manufacturers  are  prepared  to  fur- 
nish orer-size  pistons,  there  being  four  standard  over- 
size dimensions  adopted  by  the  S.  A.  E.  for  rebored 
cylinders.  These  are  .010-inch,  .020-inch,  .030-inch,  and 
.040-inch  larger  than  the  original  bore. 

The  piston  rings  should  be  taken  out  of  the  piston 
grooves  and  all  carbon  deposits  removed  from  the  inside 
of  the  ring  and  the  bottom  of  the  groove.  It  is  important 
to  take  this  deposit  out  because  it  prevents  the  rings 
from  performing  their  proper  functions  by  reducing  the 
ring  elasticity,  and  if  the  deposit  is  allowed  to  accumulate 
it  may  eventually  result  in  sticking  and  binding  of  the 
ring,  this  producing  excessive  friction  or  loss  of  compres- 
sion. When  the  rings  are  removed  they  should  be  tested 
to  see  if  they  retain  their  elasticity  and  it  is  also  well  to 
see  that  the  small  pins  in  some  pistons  which  keep  the 
rings  from  turning  around  so  the  joints  will  not  come  in 
line  are  still  in  place.  If  no  pins  are  found  there  is  no 
cause  for  alarm  because  these  dowels  are  not  always 
used.  When  fitted,  they  are  utilized  with  rings  having  a 
butt  joint  or  diagonal  cut  as  the  superior  gas  retaining 
qualities  of  the  lap  or  step  joint  render  the  pins  un- 
necessary. 

If  gas  has  been  blowing  by  the  ring  or  if  these  mem- 
bers have. not  been  fitting  the  cylinder  properly  the  points 
where  the  gas  passed  will  be  evidenced  by  burnt,  brown 
or  roughened  portions  of  the  polished  surface  of  the 
pistons  and  rings.  The  point  where  this  discoloration 
will  be  noticed  more  often  is  at  the  thin  end  of  an  eccen- 
tric ring,  the  discoloration  being  present  for  about  %-inch 
or  %-inch  each  side  of  the  slot.  It  may  be  possible  that 


438  Aviation  Engines 

the  rings  were  not  true  when  first  put  in.  This  made  it 
possible  for  the  gas  to  leak  by  in  small  amounts  initially 
which  increased  due  to  continued  pressure  until  quite  a 
large  area  for  gas  escape  had  been  created. 


PISTON   KING    MANIPULATION 

Eemoving  piston  rings  without  breaking  them  is  a  dif- 
ficult operation  if  the  proper  means  are  not  taken,  .but  is 
a  comparatively  simple  one  when  the  trick  is  known.  The 
tools  required  are  very  simple,  being  three  strips  of  thin 
steel  about  one-quarter  inch  wide  and  four  or  five  inches 
long  and  a  pair  of  spreading  tongs  made  up  of  one- 
quarter  inch  diameter  keystock  tied  in  the  center  with  a 
copper  wire  to  form  a  hinge.  The  construction  is  such 
that  when  the  hand  is  closed  and  the  handles  brought  to- 
gether the  other  end  of  the  expander  spreads  out,  an 
action  just  opposite  to  that  of  the  conventional  pliers. 
The  method  of  using  the  tongs  and  the  metal  strips  is 
clearly  indicated  at  Fig.  186.  At  A  the  ring  expander  is 
shown  spreading  the  ends  of  the  rings  sufficiently  to  insert 
the  pieces  of  sheet  metal  between  one  of  the  rings  and  the 
piston.  Grasp  the  ring  as  shown  at  B,  pressing  with  the 
thumbs  on  the  top  of  the  piston  and  the  ring  will  slide  off 
easily,  the  thin  metal  strips  acting  as  guide  members  to 
prevent  the  ring  from  catching  in  the  other  piston  grooves. 
Usually  no  difficulty  is  experienced  in  removing  the  top 
or  bottom  rings,  as  these  members  may  be  easily  expanded 
and  worked  off  directly  without  the  use  of  a  metal  strip. 
When  removing  the  intermediate  rings,  however,  the  metal 
strips  will  be  found  very  useful.  These  are  usually  made 
by  the  repairman  by  grinding  the  teeth  from  old  hacksaw 
blades  and  rounding  the  edges  and  corners  in  order  to  re- 
duce the  liability  of  cutting  the  fingers.  By  the  use  of  the 
three  metal  strips  a  ring  is  removed  without  breaking  or 
distorting  it  and  practically  no  time  is  consumed  in  the 
operation. 


Piston  Ring  Manipulation  439 

FITTING  PISTON   RINGS 

Before  installing  new  rings,  they  should  be  carefully 
fitted  to  the  grooves  to  which  they  are  applied.  The  tools 
required  are  a  large  piece  of  fine  emery  cloth,  a  thin,  flat 
file,  a  small  vise  with  copper  or  leaden  jaw  clips,  and  a 
smooth  hard  surface  such  as  that  afforded  by  the  top  of 
a  surface  plate  or  a  well  planed  piece  of  hard  wood.  After 
making  sure  that  all  deposits  of  burnt  oil  and  carbon  have 
been  removed  from  the  piston  grooves,  three  rings  are 
selected,  one  for  each  groove.  The  ring  is  turned  all 
around  its  circumference  into  the  groove  it  is  to  fit,  which 
can  be  done  without  springing  it  over  the  piston  as  the 
outside  edge  of  the  ring  may  be  used  to  test  the  width  of 
the  groove  just  as  well  as  the  inside  edge.  The  ring  should 
be  a  fair  fit  and  while  free  to  move  circumferentially  there 
should  be  no  appreciable  up  and  down  motion.  If  the 
ring  is  a  tight  fit  it  should  be  laid  edge  down  upon  the 
piece  of  emery  cloth  which  is  placed  on  the  surface  plate 
and  carefully  rubbed  down  until  it  fits  the  groove  it  is  to 
occupy.  It  is  advisable  to  fit  each  piston  ring  individually 
and  to  mark  them  in  some  way  to  insure  that  they  will  be 
placed  in  the  groove  to  which  they  are  fitted. 

The  repairman  next  turns  his  attention  to  fitting  the 
ring  in  the  cylinder  itself.  The  ring  should  be  pushed 
into  the  cylinder  at  least  two  inches  up  from  the  bottom 
and  endeavor  should  be  made  to  have  the  lower  edge  of 
the  ring  parallel  with  the  bottom  of  the  cylinder.  If  the 
ring  is  not  of  correct  diameter,  but  is  slightly  larger  than 
the  cylinder  bore,  this  condition  will  be  evident  by  the 
angular  slots  of  the  rings  being  out  of  line  or  by  difficulty 
in  inserting  the  ring  if  it  is  a  lap  joint  form.  If  such  is 
the  case  the  ring  is  removed  from  the  cylinder  and  placed 
in  the  vise  between  soft  metal  jaw  clips.  Sufficient  metal 
is  removed  with  a  fine  file  from  the  edges  of  the  ring  at 
the  slot  until  the  edges  come  into  line  and  a  slight  space 
exists  between  them  when  the  ring  is  placed  into  the  cylin- 
der. It  is  important  that  this  space  be  left  between  the 


440 


Aviation  Engines 


ends,  for  if  this  is  not  done  when  the  ring  becomes  heated 
the  expansion  of  metal  may  cause  the  ends  to  abut  and 
the  ring  to  jam  in  the  cylinder. 

It  is  necessary  to  use  more  than  ordinary  caution  in 
replacing  the  rings  on  the  piston  because  they  are  usually 


.-•Thin  Metal 


'Piston 
Ring 


Ring  Expander 

^•Clamping  Ring--'' 


Fig.  186. — Method  of  Removing  Piston  Rings,  and  Simple  Clamp  to  Facili- 
tate Insertion  of  Rings  in  Cylinder. 

made  of  cast  iron,  a  metal  that  is  very  fragile  and  liable 
to  break  because  of  its  brittleness.  Special  care  should 
be  taken  in  replacing  new  rings  as  these  members  are 


•   Piston  Ring  Manipulation  441 

more  apt  to  break  than  old  ones.  This  is  probably  ac- 
counted for  by  the  heating  action  on  used  rings  which 
tends  to  anneal  the  metal  as  well  as  making  it  less  springy. 
The  bottom  ring  should  be  placed  in  position  first  which 
is  easily  accomplished  by  springing  the  ring  open  enough 
to  pass  on  the  piston  and  then  sliding  it  into  place  in  the 
lower  groove  which  on  some  types  of  engines  is  below 
the  wrist  pin,  whereas  in  others  all  grooves  are  above  that 
member.  The  other  members  are  put  in  by  a  reversal  of 
the  process  outlined  at  Fig.  186,  A  and  B.  It  is  not  always 
necessary  to  use  the  guiding  strips  of  metal  when  replac- 
ing rings  as  it  is  often  possible,  by  putting  the  rings  on 
the  piston  a  little  askew  and  maneuvering  them  to  pass 
the  grooves  without  springing  the  ring  into  them.  The 
top  ring  should  be  the  last  one  placed  in  position. 

Before  placing  pistons  in  the  cylinder  one  should  make 
sure  that  the  slots  in  the  piston  rings  are  spaced  equidis- 
tant on  the  piston,  and  if  pins  are  used  to  keep  the  ring 
from  turning  one  should  be  careful  to  make  sure  that  these 
pins  fit  into  their  holes  in  the  ring  and  that  they  are  not 
under  the  ring  at  any  point.  Practically  all  cylinders  are 
chamfered  at  the  lower  end  to  make  insertion  of  piston 
rings  easier.  The  operation  of  putting  on  a  cylinder  cast- 
ing over  a  piston  really  requires  two  pairs  of  hands,  one 
to  manipulate  the  cylinder,  the  other  person  to  close  the 
rings  as  they  enter  the  cylinder.  This  may  be  done  very 
easily  by  a  simple  clamp  member  made  of  sheet  brass  or 
iron  and  used  to  close  the  ring  as  indicated  at  Fig.  186,  C. 
It  is  apparent  that  the  clamp  must  be  adjusted  to  each 
individual  ring  and  that  the  split  portion  of  the  clamp 
must  coincide  with  the  split  portion  of  the  ring.  The 
cylinder  should  be  well  oiled  before  any  attempt  is  made  to 
install  the  pistons.  The  engine  should  be  run  with  more 
than  the  ordinary  amount  of  lubricant  for  several  hours 
after  new  piston  rings  have  been  inserted.  On  first  start- 
ing the  engine,  one  may  be  disappointed  in  that  the  com- 
pression is  even  less  than  that  obtained  with  the  old  rings. 
This  condition  will  soon  be  remedied  as  the  rings  become 


442  Aviation  Engines 

polished   and   adapt    themselves    to    the    contour    of   the 
cylinder. 

WRIST  PIN  WEAR 

While  wrist  pins  are  usually  made  of  very  tough  steel, 
case  hardened  with  the  object  of  wearing  out  an  easily 
renewable  bronze  bushing  in  the  upper  end  of  the  connect- 
ing rod  rather  than  the  wrist  pin  it  sometimes  happens 
that  these  members  will  be  worn  so  that  even  the  re- 
placement of  a  new  bushing  in  the  connecting  rod  will 
not  reduce  the  lost  motion  and  attendant  noise  due  to  a 
loose  wrist  pin.  The  only  remedy  is  to  fit  new  wrist  pins 
to  the  piston.  Where  the  connecting  rod  is  clamped  to 
the  wrist  pin  and  that  member  oscillates  in  the  piston 
bosses  the  wear  will  usually  be  indicated  on  bronze  bush- 
ings which  are  pressed  into  the  piston  bosses.  These  are 
easily  renewed  and  after  running  a  reamer  through  them 
of  the  proper  size  no  difficulty  should  be  experienced  in 
replacing  either  the  old  or  a  new  wrist  pin  depending 
upon  the  condition  of  that  member.  If  no  bushings  are 
provided,  as  in  alloy  pistons,  the  bosses  can  sometimes 
be  bored  out  and  thin  bushings  inserted,  though  this  is 
not  always  possible.  The  alternative  is  to  ream  out  the 
bosses  and  upper  end  of  rod  a  trifle  larger  after  holes  are 
trued  up  and  fit  oversize  wrist  pins. 

INSPECTION    AND    REFITTING    OF    ENGINE    BEARINGS     , 

While  the  engine  is  dismantled  one  has  an  excellent 
opportunity  to  examine  the  various  bearing  points  in  the 
engine  crank-case  to  ascertain  if  any  looseness  exists  due 
to  depreciation  of  the  bearing  surfaces.  As  will  be  evi- 
dent, both  main  crank-shaft  bearings  and  the  lower  end 
of  the  connecting  rods  may  be  easily  examined  for  de- 
terioration. With  the  rods  in  place,  it  is  not  difficult  to 
feel  the  amount  of  lost  motion  by  grasping  the  connect- 
ing rod  firmly  with  the  hand  and  moving  it  up  and  down. 
After  the  connecting  rods  have  been  removed  and  the 


Refitting  Engine  Bearings  443 

propeller  hub  taken  off  the  crank-shaft  to  permit  of  ready 
handling,  any  looseness  in  the  main  bearing  may  be  de- 
tected by  lifting  up  on  either  the  front  or  rear  end  of 
the  crank-shaft  and  observing  if  there  is  any  lost  motion 
between  the  shaft  journal  and  the  main  bearing  caps. 
It  is  not  necessary  to  take  an  engine  entirely  apart  to 
examine  the  main  bearings,  as  in  most  forms  these  may  be 
readily  reached  by  removing  the  sump.  The  symptoms 
of  worn  main  bearings  are  not  hard  to  identify.  If  an 
engine  knocks  regardless  of  speed  or  spark-lever  position, 
and  the  trouble  is  not  due  to  carbon  deposits  in  the  com- 
bustion chamber,  one  may  reasonably  surmise  that  the 
main  bearings  have  become  loos.e  or  that  lost  motion  may 
exist  at  the  connecting  rod  big  ends,  and  possibly  at  the 
wrist  pins.  The  main  journals  of  any  well  resigned  en- 
gine are  usually  proportioned  with  ample  surface  and 
will  not  wear  unduly  unless  lubrication  has  been  neg- 
lected. The  connecting  rod  bearings  wear  quicker  than 
the  main  bearings  owing  to  being  subjected  to  a  greater 
unit  stress,  and  it  may  be  necessary  to  take  these  up. 


ADJUSTING   MAIN   BEARINGS 

When  the  bearings  are  not  worn  enough  to  require 
refitting  the  lost  motion  can  often  be  eliminated  by  re- 
moving one  or  more  of  the  thin  shims  or  liners  ordinarily 
used  to  separate  the  bearing  caps  from  the  seat.  These 
are  shown  at  Fig.  187,  A.  Care  must  be  taken  that  an 
even  number -of  shims  of  the  same  thickness  are  removed 
from  each  side  of  the  journal.  If  there  is  considerable 
lost  motion  after  one  or  two  shims  have  been  removed, 
it  will  be  advisable  to  take  out  more  shims  and  to  scrape 
the  bearing  to  a  fit  before  the  bearing  cap  is  tightened 
up.  It  may  be  necessary  to  clean  up  the  crank- shaft 
journals  as  these  may  be  scored  due  to  not  having  re- 
ceived clean  oil  or  having  had  bearings  seize  upon  them. 
It  is  not  difficult  to  true  up  the  crank-pins  or  main  jour- 
nals if  the  score  marks  are  not  deep.  A  fine  file  and 


,>-Emery  Cloth 


Shims, 


"•'  Box 


Bearing 
Cap --'    A 


Tig.  187. — Tools  and  Processes  Used  in  Befitting  Engine  Bearings. 

444 


Refitting  Engine  Bearings  445 

emery  cloth  may  be  used,  or  a  lapping  tool  such  as  de- 
picted at  Fig.  187,  B.  The  latter  is  preferable  because 
the  file  and  emery  cloth  will  only  tend  to  smooth  the  sur- 
face while  the  lap  will  have  the  effect  of  restoring  the 
crank  to  proper  contour. 

A  lapping  tool  may  be  easily  made,  as  shown  at  B,  the 
blocks  being  of  lead  or  hard  wood.  As  the  width  of  these 
are  about  half  that  of  the  crank-pin  the  tool  may  be 
worked  from  side  to  side  as  it  is  rotated.  An  abrasive 
paste  composed  of  fine  emery  powder  and  oil  is  placed 
between  the  blocks,  and  the  blocks  are  firmly  clamped  to 
the  crank-pin.  As  the  lead  blocks  bed  down,  the  wing 
nut  should  be  tightened  to  insure  that  the  abrasive  will  be 
held  with  some  degree  of  pressure  against  the  shaft.  A 
liberal  supply  of  new  abrading  material  is  placed  between 
the  lapping  blocks  and  crank-shaft  from  time  to  time  and 
the  old  mixture  cleaned  off  with  gasoline.  It  is  necessary 
to  maintain  a  side  to  side  movement  of  the  lapping  tool 
in  order  to  have  the  process  affect  the  whole  width  of  the 
crank-pin  equally.  The  lapping  is  continued  until  a 
smooth  surface  is  obtained.  If  a  crank-pin  is  worn  out 
of  true  to  any  extent  the  only  method  of  restoring  it  is 
to  have  it  ground  down  to  proper  circular  form  by  a 
competent  mechanic  having  the  necessary  machine  tools 
to  carry  on  the  work  accurately.  A  crank-pin  truing 
tool  that  may  be  worked  by  hand  is  shown  at  Fig.  187,  K. 

After  the  crank-shaft  is  trued  the  next  operation  is  to 
fit  it  to  the  main  bearings  or  rather  to  scrape  these  mem- 
bers to  fit  the  shaft  journal.  In  order  to  bring  the  brasses 
closer  together,  it  may  be  necessary  to  remove  a  little 
metal  from  the  edges  of  the  caps  to  compensate  for  the 
lost  motion.  A  very  simple  way  of  doing  this  is  shown 
at  Fig.  187,  D.  A  piece  of  medium  emery  cloth  is  rested 
on  the  surface  plate  and  the  box  or  brass  is  pushed  back 
and  forth  over  that  member  by  hand,  the  amount  of  pres- 
sure and  rapidity  of  movement  being  determined  by  the 
amount  of  metal  it  is  necessary  to  remove.  This  is  better 
than  filing,  because  the -edges  will  be  flat  and  there  will  be 


446  Aviation  Engines 

no  tendency  for  the  bearing  caps  to  rock  when  placed 
against  the  bearing  seat.  It  is  important  to  take  enough 
off  the  edges  of  the  boxes  to  insure  that  they  will  grip 
the  crank  tightly.  The  outer  diameter  must  be  checked 
with  a  pair  of  calipers  during  this  operation  to  make  sure 
that  the  surfaces  remain  parallel.  Otherwise,  the  bearing 
brasses  will  only  grip  at  one  end  and  with  such  insuffi- 
cient support  they  will  quickly  work  loose,  both  in  the 
bearing  seat  and  bearing  cap. 


SCRAPING    BRASSES    TO    FIT 

To  insure  that  the  bearing  brasses  will  be  a  good  fit 
on  the  trued-up  crank-pins  or  crank-shaft  journals,  they 
must  be  scraped  to  fit  the  various  crank-shaft  journals. 
The  process  of  scraping,  while  a  tedious  one,  is  not  diffi- 
cult, requiring  only  patience  and  some  degree  of  care  to 
do  a  good  job.  The  surface  of  the  crank-pin  is  smeared 
with  Prussian  blue  pigment  which  is  spread  evenly  over 
the  entire  surface.  The  bearings  are  then  clamped  to- 
gether in  the  usual  manner  with  the  proper  bolts,  and  the 
crank-shaft  revolved  several  times  to  indicate  the  high 
spots  on  the  bearing  cap.  At  the  start  of  the  process  of 
scraping  in,  the  bearing  may  seat  only  at  a  few  points  as 
shown  at  Fig.  187,  G.  Continued  scraping  will  bring  the 
bearing  surface  as  indicated  at  H,  whichr  is  a  consider- 
able improvement,  while  the  process  may  be  considered 
complete  when  the  brass  indicates  a  bearing  all  over  as 
at  I.  The  high  spots  are  indicated  by  blue,  as  where  the 
shaft  does  not  bear  on  the  bearing  there  is  no  color. 
The  high  spots  are  removed  by  means  of  a  scraping  tool 
of  the  form  shown  at  Fig.  187,  F,  which  is  easily  made 
from  a  worn-out  file.  These  are  forged  to  shape  and 
ground  hollow  as  indicated  in  the  section,  and  are  kept 
properly  sharpened  by  frequent  rubbing  on  an  ordinary 
oil  stone.  To  scrape  properly,  the  edge  of  the  scraper 
must  be  very  keen.  The  straight  and  curved  half-round 
scrapers,  shown  at  M  and  N,  are  used  for  bearings.  The 


Refitting  Engine  Bearings  447 

three-cornered  scraper,  outlined  at  0,  is  also  used  on 
curved  surfaces,  and  is  of  value  in  rounding  off  the  sharp 
corners.  The  straight  or  curved  half-round  type  works 
well  on  soft-bearing  metals,  such  as  babbitt,  or  white  brass, 
but  on  yellow  brass  or  bronze  it  cuts  very  slowly,  and  as 
soon  as  the  edge  becomes  dull  considerable  pressure  is 
needed  to  remove  any  metal,  this  calling  for  frequent 
sharpening. 

When  correcting  errors  on  flat  or  curved  surfaces  by 
hand- scraping,  it  is  desirable,  of  course,  to  obtain  an 
evenly  spotted  bearing  with  as  little  scraping  as  possible. 
When  the  part  to  be  scraped  is  first  applied  to  the  sur- 
face-plate, or  to  a  journal  in  the  case  of  a  bearing,  three 
or  four  "high"  spots  may  be  indicated  by  the  marking 
material.  The  time  required  to  reduce  these  high  spots 
and  obtain  a  bearing  that  is  distributed  over  the  entire 
surface  depends  largely  upon  the  way  the  scraping  is 
started.  If  the  first  bearing  marks  indicate  a  decided 
rise  in  the  surface,  much  time  can  be  saved -by  scraping 
larger  areas  than  are  covered  by  the  bearing  marks;  this 
is  especially  true  of  large  shaft  and  engine  bearings,  etc. 
An  experienced  workman  will  not  only  remove  the  heavy 
marks,  but  also  reduce  a  larger  area ;  then,  when  the 
bearing  is  tested  again,  the  marks  will  generally  be  dis- 
tributed somewhat.'  If  the  heavy  marks  which  usually 
appear  at  first  are  simply  removed  by  light  scraping, 
these  "point  bearings"  are  gradually  enlarged,  but  a 
much  longer  time  will  be  required  to  distribute  them. 

The  number  of  times  the  bearing  must  be  applied  to 
the  journal  for  testing  is  important,  especially  when  the 
box  or  bearing  is  large  and  not  easily  handled.  The  time 
required  to  distribute  the  bearing  marks  evenly  depends 
largely  upon  one's  judgment  in  "reading"  these  marks. 
In  the  early  stages  of  the  scraping  operation,  the  marks 
should  be  used  partly  as  a  guide  for  showing  the  high 
areas,  and  instead  of  merely  scraping  the  marked  spot 
the  surface  surrounding  it  should  also  be  reduced,  unless 
it  is  evident  that  the  unevenness  is  local.  The  idea  should 


448  Aviation  Engines 

be  to  obtain  first  a  few  large  but  generally  distributed 
marks;  then  an  evenly  and  finely  spotted  surface  can  be 
produced  quite  easily. 

In  fitting  brasses  when  these  are  of  .the  removable 
type,  two  methods  may  be  used.  The  upper  half  of  the 
engine  base  may  be  inverted  on  a  suitable  bench  or  stand 
and  the  boxes  fitted  by  placing  the  crank-shaft  in  position, 
clamping  down  one  bearing  cap  at  a  time  and  fitting  each 
bearing  in  succession  until  they  bed  equally.  From  that 
time  on  the  bearings  should  be  fitted  at  the  same  time 
so  the  shaft  will  be  parallel  with  the  bottom  of  the  cylin- 
ders. Considerable  time  and  handling  of  the  heavy  crank- 
shaft may  be  saved  if  a  preliminary  fitting  of  the  bearing 
brasses  is  made  by  clamping  them  together  with  a  car- 
penter ?s  wood  clamp  as  shown  at  Fig.  187,  J,  and  leaving 
the  crank-shaft  attached  to  the  bench  as  shown  at  C. 
The  brasses  are  revolved  around  the  crank-shaft  journal 
and  are  scraped  to  fit  wherever  high  spots  are  indicated 
until  they  begin  to  seat  fairly.  When  the  brasses  assume 
a  finished  appearance  the  final  scraping  should  be  carried 
on  with  all  bearings  in  place  and  revolving  the  crank- 
shaft to  determine  the  area  of  the  seating.  When  the 
brasses  are  properly  fitted  they  will  not  only  show  a  full 
bearing  surface,  but  the  shaft  will  not  turn  unduly  hard 
if  revolved  with  a  moderate  amount  of  leverage. 

Bearings  of  white  metal  or  babbitt  can  be  fitted  tighter 
than  those  of  bronze,  and  care  must  be  observed  in  sup- 
plying lubricant  as  considerably  more  than  the  usual 
amount  is  needed  until  the  bearings  are  run  in  by  several 
hours  of  test  block  work.  Before  the  scraping  process 
is  started  it  is  well  to  chisel  an  oil  groove  in  the  bearing 
as  shown  at  Fig.  187,  L.  Grooves  are  very  helpful  in 
insuring  uniform  distribution  of  oil  over  the  entire  width 
of  bearing  and  at  the  same  time  act  as  reservoirs  to  retain 
a  supply  of  oil.  The  tool  used  is  a  round-nosed  chisel, 
the  effort  being  made  to  cut  the  grooves  of  uniform 
depth  and  having  smooth  sides.  Care  should  be  taken 
not  to  cut  the  grooves  too  deeply,  as  this  will  seriously 


'  Fitting  Connecting  Rods  449 

reduce  the  strength  of  the  bearing  bushing.  The  shape 
of  the  groove  ordinarily  provided  is  clearly  shown  at 
Fig.  187,  Gr,  and  it  will  be  observed  that  the  grooves  do 
not  extend  clear  to  the  edge  of  the  bearing,  but  stop  about 
a  quarter  of  an  inch  from  that  point.  The  hole  through 
which  the  oil  is  supplied  to  the  bearing  is  usually  drilled 
in  such  a  way  that  it  will  communicate  with  the  groove. 

The  tool  shown  at  Fig.  187,  K,  is  of  recent  develop- 
ment, and  is  known  as  a  "crank-shaft  equalizer."  This 
is  a  hand-operated  turning  tool,  carrying  cutters  which  are 
intended  to  smooth  down  scored  crank-pins  without  using 
a  lathe.  The  feed  may  be  adjusted  by  suitable  screws 
and  the  device  may  be  fitted  to  crank-pins  and  shaft - 
journals  of  different  diameters  by  other  adjusting  screws. 
This  device  is  not  hard  to  operate,  being  merely  clamped 
around  the  crank- shaft  in  the  same  manner  as  the  lapping 
tool  previously  described,  and  after  it  has  been  properly 
adjusted  it  is  turned  around  by  the  levers  provided  for 
the  purpose,  the  continuous  rotary  motion  removing  the 
metal  just  as  a  lathe  tool  would. 

FITTING    CONNECTING    EODS 

In  the  marine  type  rod,  which  is  the  form  generally 
used  in  airplane  engines,  one  or  two  bolts  are  employed 
at  each  side  and  the  cap  must  be  removed  entirely  before 
the  bearing  can  be  taken  off  of  the  crank-pin.  The  tight- 
ness of  the  brasses  around  the  crank-pin  can  never  be 
determined  solely  by  the  adjustment  of  the  bolts,  as  while 
it  is  important  that  these  should  be  drawn  up  as  tightly 
as  possible,  the  bearing  should  fit  the  shaft  without  undue 
binding,  even  if  the  brasses  must  be  scraped  to  insure 
a  proper  fit.  As  is  true  of  the  main  bearings,  the  marine 
form  of  connecting  rod  in  some  engines  has  a  number  of 
liners  or  shims  interposed  between  the  top  and  lower 
portions  of  the  rod  end,  and  these  may  be  reduced  in 
number  when  necessary  to  bring  the  brasses  closer  to- 
gether. The  general  tendency  in  airplane  engines  is  to 


450 


Aviation  Engines 


eliminate  shims  in  either  the  main  or  connecting  rod  bear- 
ings, and  when  wear  is  noticed  the  boxes  or  liners  are 
removed  and  new  ones  supplied.  The  brasses  are  held 
in  the  connecting  rod  and  cap  by  brass  rivets  and  are 
generally  attached  in  the  main  bearing  by  small  brass 
machine  screws.  The  form  of  box  generally  favored  is 
a  brass  sand  casting  rich  in  copper  to  secure  good  heat 
conductivity  which  forms  a  backing  for  a  thin  layer  of 
white  brass,  babbitt  or  similar  anti-friction  metal. 

In  fitting  new  brasses  there  are  two  conditions  to  be 
avoided,  these  being  outlined  at  Fig.  188,  B  and  C.     In 


Retaining  Bolts 
A 


"Retaining  Bolts-: 

•B 


•Retaining  Bolts- 
C 


Fig.    188. — Showing    Points    to    Observe    When   Fitting    Connecting    Bod 

Brasses. 

the  case  shown  at  C  the  light  edges  of  the  bushings  are 
in  contact,  but  the  connecting  rod  and  its  cap  do  not  meet. 
When  the  retaining  nuts  are  tightened  the  entire  strain 
is  taken  on  the  comparatively  small  area  of  the  edges  of 
the  bushings  which  are  not  strong  enough  to  withstand 
the  strains  existing  and  which  flatten  out  quickly,  per- 
mitting the  bearing  to  run  loose.  In  the  example  out- 
lined at  B  the  edges  of  the  brasses  do  not  touch  when 
the  connecting  rod  cap  is  drawn  in  place.  This  is  not 
good  practice,  because  the  brasses  soon  become  loose  in 
their  retaining  member.  In  the  case  outlined  it  is  neces- 


Testing  Sprung  Cam-shaft  451 

sary  to  file  off  the  faces  of  the  rod  and  cap  until  these 
meet,  and  to  insure  contact  of  the  edges  of  the  brasses 
as  well.  In  event  of  the  brasses  coming  together  before 
the  cap  and  rod  make  contact,  as  shown  at  C,  the  bearing 
halves  should  be  reduced  at  the  edges  until  both  the  caps 
and  brasses  meet  against  each  other  or  the  surfaces  of 
the  liners  as  shown  at  A. 


SPRUNG   CAM-SHAFT 

If  the  cam-shaft  is  sprung  or  twisted  it  will  alter  the 
valve  timing  to  such  an  extent  that  the  smoothness  of 
operation  of  the  engine  will  be  materially  affected.  If 
this  condition  is  suspected  the  cam-shaft  may  be  swung 
on  lathe  centers  and  turned  to  see  if  it  runs  out  and  can 
be  straightened  in  any  of  the  usual  form  of  shaft-straight- 
ening machines.  The  shaft  may  be  twisted  without  being 
sprung.  This  can  only  be  determined  by  supporting  one 
end  of  the  shaft  in  an  index  head  and  the  other  end  on 
a  milling  machine  center.  The  cams  are  then  checked  to 
see  that  they  are  separated  by  the  proper  degree  of  angu- 
larity. This  process  is  one  that  requires  a  thorough 
knowledge  of  the  valve  timing  of  the  engine  in  question, 
and  is  best  done  at  the  factory  where  the  engine  was 
made.  The  timing  gears  should  also  be  examined  to  see 
if  the  teeth  are  worn  enough  so  that  considerable  back 
lash  or  lost  motion  exists  between  them.  This  is  espe- 
cially important  where  worm  or  spiral  gears  are  used. 
A  worn  timing  gear  not  only  produces  noise,  but  it  will 
cause  the  time  of  opening  and  closing  of  the  engine  valves 
to  vary  materially. 

PRECAUTIONS    IN    REASSEMBLING    PARTS 

When  all  of  the  essential  components  of  a  power  plant 
have  been  carefully  looked  over  and  cleaned  and  all  de- 
fects eliminated,  either  by  adjustment  or  replacement  of 
worn  portions,  the  motor  should  be  reassembled,  taking 


452  Aviation  Engines 

care  to  have  the  parts  occupy  just  the  same  relative  posi- 
tions they  did  before  the  motor  was  dismantled.  As  each 
part  is  added  to  the  assemblage  care  should  be  taken  to 
insure  adequate  lubrication  of  all  new  points  of  bearing 
by  squirting  liberal  quantities  of  cylinder  oil  upon  them 
with  a  hand  oil  can  or  syringe  provided  for  the  purpose. 
In  adjusting  the  crank-shaft  bearings,  tighten  them  one 
at  a  time  and  revolve  the  shafts  each  time  one  of  the 
bearing  caps  is  set  up  to  insure  that  the  newly  adjusted 
bearing  does  not  have  undue  friction.  All  retaining  keys 
and  pins  must  be  positively  placed  and  it  is  good  practice 
to  cover  such  a  part  with  lubricant  before  replacing  it 
because  it  will  not  only  drive  in  easier,  but  the  part  may 
be  removed  more  easily  if  necessary  at  some  future  time. 
If  not  oiled,  rust  collects  around  it. 

"When  a  piece  is  held  by  more  than  one  bolt  or  screw, 
especially  if  it  is  a  casting  of  brittle  material  such  as 
cast  iron  or  aluminum,  the  fastening  bolts  should  be  tight- 
ened uniformly.  If  one  bolt  is  tightened  more  than  the 
rest  it  is  liable  to  spring  the  casting  enough  to  break  it. 
Spring  washers,  check  nuts,  split  pins  or  other  locking 
means  should  always  be  provided,  especially  on  parts 
which  are  in  motion  or  subjected  to  heavy  loads. 

Before  placing  the  cylinder  over  the  piston  it  is  im- 
perative that  the  slots  in  the  piston  rings  are  spaced 
equidistant  and  that  the  piston  is  copiously  oiled  before 
the  cylinder  is  slipped  over  it.  "When  reassembling  the 
inlet  and  exhaust  manifolds  it  is  well  to  use  only  perfect 
packings  or  gaskets  and  to  avoid  the  use  of  those  that 
seem  to  have  hardened  up  or  flattened  out  too  much  in 
service.  If  it  is  necessary  to  use  new  gaskets  it  is  im- 
perative to  employ  these  at  all  joints  on  a  manifold,  be- 
cause if  old  and  new  gaskets  are  used  together  the  new 
ones  are  apt  to  keep  the  manifold  from  bedding  properly 
upon  the  used  ones.  It  is  well  to  coat  the  threads  of  all 
bolts  and  screws  subjected  to  heat,  such  as  cylinder  head 
and  exhaust  manifold  retaining  bolts,  with  a  mixture  of 
graphite  and  oil.  Those  that  enter  the  water  jacket  should 


Reassembling  Parts  453 

be  covered  with  white  or  red  lead  or  pipe  thread  com- 
pound. Gaskets  will  hold  better  if  coated  with  shellac 
before  the  manifold  or  other  parts  are  placed  over  them. 
The  shellac  fills  any  irregularities  in  the  joint  and  assists 
materially  in  preventing  leakage  after  the  joint  is  made 
up  and  the  coating  has  a  chance  to  set. 

Before  assembling  on  the  shaft,  it  is  necessary  to  fit 
the  bearings  by  scraping,  the  same  instructions  given  for 
restoring  the  contour  of  the  main  bearings  applying  just 
as  well  in  this  case.  It  is  apparent  that  if  the  crank-pins 
are  not  round  no  amount  of  scraping  will  insure  a  true 
bearing.  A  point  to  observe  is  to  make  sure  that  the 
heads  of  the  bolts  are  imbedded  solidly  in  their  proper 
position,  and  that  they  are  not  raised  by  any  burrs  or 
particles  of  dirt  under  the  head  which  will  flatten  out 
after  the  engine  has  been  run  for  a  time  and  allow  the 
bolts  to  slack  off.  Similarly,  care  should  be  taken  that 
there  is  no  foreign  matter  under  the  brasses  and  the 
box  in  which  they  seat.  To  guard  against  this  the  bolts 
should  be  struck  with  a  hammer  several  times  after  they 
are  tightened  up,  and  the  connecting  rod  can  be  hit 
sharply  several  times  under  the  cap  with  a  wooden  mallet 
or  lead  hammer.  It  is  important  to  pin  the  brasses  in 
place  to  prevent  movement,  as  lubrication  may  be  inter- 
fered with  if  the  bushing  turns  round  and  breaks  the  cor- 
rect register  between  the  oil  hole  in  the  cap  and  brasses. 

Care  should  be  taken  in  screwing  on  the  retaining  nuts 
to  insure  that  they  will  remain  in  place  and  not  slack  off. 
Spring  washers  should  not  be  used  on  either  connecting 
rod  ends  or  main  bearing  nuts,  because  these  sometimes 
snap  in  two  pieces  and  leave  the  nut  slack.  The  best 
method  of  locking  is  to  use  well-fitting  split  pins  and 
castellated  nuts. 

TESTING     BEARING     PARALLELISM 

It  is  not  possible  to  give  other  than  general  directions 
regarding  the  proper  degree  of  tightening  for  a  con- 
necting rod  bearing,  but  as  a  guide  to  correct  adjustment 


454  Aviation  Engines 

it  may  be  said  that  if  the  connecting  rod  cap  is  tightened 
sufficiently  so  the  connecting  rod  will  just  about  fall  over 
from  a  vertical  position  due  to  the  piston  weight  when 
the  bolts  are  fully  tightened  up,  the  adjustment  will  be 
nearly  correct.  As  previously  stated,  babbitt  or  white 
metal  bearings  can  be  set  up  more  tightly  than  bronze, 
as  the  metal  is  softer  and  any  high  spots  will  soon  be 
leveled  down  with  the  running  of  the  engine.  It  is  im- 
portant that  care  be  taken  to  preserve  parallelism  of 
the  wrist-pins  and  crank-shafts  while  scraping  in  bear- 
ings. This  can  be  determined  in  two  ways.  That  shown 
at  Fig.  189,  A,  is  used  when  the  parts  are  not  in  the 
engine  assembly  and  when  the  connecting  rod  bearing  is 
being  fitted  to  a  mandrel  or  arbor  the  same  size  as  the 
crank-pin.  The  arbor,  which  is  finished  very  smooth  and 
of  uniform  diameter,  is  placed  in  two  V  blocks,  which  in 
turn  are  supported  by  a  level  surface  plate.  An  ad- 
justable height  gauge  may  be  tried,  first  at  one  side  of 
the  wrist-pin  which  is  placed  at  the  upper  end  of  the 
connecting  rod,  then  at  the  other,  and  any  variation  will 
be  easily  determined  by  the  degree  of  tilting  of  the  rod. 
This  test  may  be  made  with  the  wrist-pin  alone,  or  if 
the  piston  is  in  place,  a  straight  edge  or  spirit  level  may 
be  employed.  The  spirit  level  will  readily  show  any  in- 
clination while  the  straight  edge  is  used  in  connection 
with  the  height  gauge  as  indicated.  Oi  course,  the  sur- 
face plate  must  be  absolutely  level  when  tests  are  made. 
When  the  connecting  rods  are  being  fitted  with  the 
crank-shaft  in  place  in  crank-case,  and  that  member  se- 
cured in  the  frame,  a  steel  square  may  be  used  as  it  is 
reasonable  to  assume  that  the  wrist-pin,  and  consequently 
the  piston,  it  carries,  should  observe  a  true  relation  with 
the  top  of  the  engine  base.  If  the  piston  side  is  at  right 
angles  with  the  top  of  the  engine  base  it  is  reasonable 
to  assume  that  the  wrist-pin  and  crank-pin  are  parallel. 
If  the  piston  is  canted  to  one  side  or  the  other,  it  will 
indicate  that  the  brasses  have  been  scraped  tapering, 
which  would  mean  considerable  heating  and  undue  .fric- 


Testing  Bearing  Parallelism 


455 


tion  if  the  piston  is  installed  in  the  cylinder  on  account 
of  the  pressure  against  one  portion  of  the  cylinder  wall. 
If  the  degree  of  canting  is  not  too  great,  the  connecting 
rods  may  be  sprung  very  slightly  to  straighten  up  the 


Height 


-Piston 


Mandrel ' 


Mandrel* 
V-Block 


/-Straight  Edge 


......Connecting  Rod 

V- Block 


Surface  Plate--'" 


.-Piston 


>  Cylinder  Bed 


''  Center  Bearinq        \  _ 
Front  Bearing  "End Bearing 

B 


Fig.   189. — Methods  of  Testing  to  Insure  Parallelism   of  Bearings  After 

Fitting. 

piston,  but  this  is  a  makeshift  that  is  not  advised.  The 
height  gauge  method  shown  above  may  be  used  instead 
of  the  steel  square,  if  desired,  because  the  top  of  the 
crank-case  is  planed  or  milled  true  and  should  be  parallel 
with  the  center  line  of  the  crank-shaft. 


456  Aviation  Engines 

CAM-SHAFTS    AND    TIMING    GEARS 

Knocking  sounds  are  also  evident  if  the  cam-shaft  is 
loose  in  its  bearings,  and  also  if  the  cams  or  timing 
gears  are  loose  on  the  shaft.  The  cam-shaft  is  usually 
supported  by  solid  bearings  of  the  removable  bushing 
type,  having  no  compensation  for  depreciation.  If  these 
bearings  wear  the  only  remedy  is  replacement  with  new 
ones.  In  the  older  makes  of  cars  it  was  general  practice 
to  machine  the  cams  separately  and  to  secure  these  to  the 
cam-shaft  by  means  of  taper  pins  or  keys.  These  mem- 
bers sometimes  loosened  and  caused  noise.  In  the  event 
of  the  cams  being  loose,  care  should  be  taken  to  use  new 
keys  or  taper  pins,  as  the  case  may  be.  If  the  fastening 
used  was  a  pin,  the  hole  through  the  cam-shaft  will 
invariably  be  slightly  oval  from  wear.  In  order  to  insure 
a  tight  job,  the  holes  in  cam  and  shaft  must  be  reamed 
with  the  next  larger  size  of  standard  taper  reamer  and 
a  larger  pin  driven  in.  Another  point  to  watch  is  the 
method  of  retaining  the  cam-shaft  gear  in  place.  On 
some  engines  the  gear  is  fastened  to  a  flange  on  the 
cam-shaft  by  retaining  screws.  These  are  not  apt  to 
become  loose,  but  where  reliance  is  placed  on  a  key  the 
cam-shaft  gear  may  often  be  loose  on  its  supporting 
member.  The  only  remedy  is  to  enlarge  the  key  slot 
in  both  gear  and  shaft  and  to  fit  a  larger  retaining  key. 


CHAPTER   XII 

Aviation  Engine  Types — Division  in  Classes — Anzani  Engines — Canton 
and  Unne  Engine — Construction  of  Gnome  Engines — "Monosou- 
pape"  Gnome — German  "Gnome"  Type — Le  Rhone  Engine — 
Renault  Air-Cooled  Engine — Simplex  Model  "A"  Hispana-Suiza 
— Curtiss  Aviation  Motors — Thomas-Morse  Model  88  Engine — 
Duesenberg  Engine — Aeromarine  Six-Cylinder — Wisconsin  Avia- 
tion Engines — Hall-Scott  Engines — Mercedes  Motor — Benz  Motor 
— Austro-Daimler — Sunbeam-Coatalen. 


AVIATION  ENGINE   TYPES 

Inasmuch  as  numerous  forms  of  airplane  engines  have 
been  devised,  it  would  require  a  volume  of  considerable 
size  to  describe  even  the  most  important  developments 
of  recent  years.  As  considerable  explanatory  matter  has 
been  given  in  preceding  chapters  and  the  principles  in- 
volved in  internal  combustion  engine  operation  consid- 
ered in  detail,  a  relatively  brief  review  of  the  features 
of  some  of  the  most  successful  airplane  motors  should 
suffice  to  give  the  reader  a  complete  enough  understand- 
ing of  the  art  so  all  types  of  engines  can  be  readily 
recognized  and  the  advantages  and  disadvantages  of  each 
type  understood,  as  well  as  defining  the  constructional 
features  enough  so  the  methods  of  locating  and  repair- 
ing the  common  engine  and  auxiliary  system  troubles 
will  be  fully  grasped.. 

Aviation  engines  can  be  divided  into  three  main 
classes.  One  of  the  earliest  attempts  to  devise  distinctive 
power  plant  designs  for  aircraft  involved  the  construc- 
tion of  engines  utilizing  a  radial,  arrangement  of  the 
cylinders  or  a  star-wise  disposition.  Among  the  engines 
of  this  class  may  be  mentioned  the  Anzani,  B.  E.  P.  and 
the  Salmson  or  Canton  and  Unne  forms.  The  two  former 
are  air-cooled,  the  latter  design  is  water-cooled.  Engines 

457 


458  Aviation  Engines 

of  this  type  have  been  built  in  cylinder  numbers  ranging 
from  three  to  twenty.  While  the  simple  forms  were 
popular  in  the  early  days  of  aviation  engine  develop- 
ment, they  have  been  succeeded  by  the  more  conventional 
arrangements  which  now  form  the  largest  class.  The 
reason  for  the  adoption  of  a  star-wise  arrangement  of 
cylinders  has  been  previously  considered.  Smoothness 
of  running  can  only  be  obtained  by  using  a  considerable 
number  of  cylinders.  .  The  fundamental  reason  for  the 
adoption  of  the  star-wise  disposition  is  that  a  better  dis- 
tribution of  stress  is  obtained  by  having  all  of  the  pistons 
acting  on  the  same  crank-pin  so  that  the  crank-throw  and 
pin  are  continuously  under  maximum  stress.  Some  diffi- 
culty has  been  experienced  in  lubricating  the  lower  cylin- 
ders in  some  forms  of  six  cylinder,  rotary  crank,  radial 
engines  but  these  have  been  largely  overcome  so  they  are 
not  as  serious  in  practice  as  a  theoretical  consideration 
would  indicate. 

Another  class  of  engines  developed  to  meet  aviation 
requirements  is  a  complete  departure  from  the  preceding 
class,  though  when  the  engines  are  at  rest,  it  is  difficult 
to  differentiate  between  them.  This  class  includes  en- 
gines having  a  star-wise  disposition  of  the  cylinders  but 
the  cylinders  themselves  and  the  crank-case  rotate  and 
the  crank-shaft  remains  stationary.  The  important  rotary, 
engine^  are  the  Gnome,  the  Le  Ehone  and  the  Clerget. 
By  far  the  most  important  classification  is  that  includ- 
ing engines  which  retain  the  approved  design  of  the 
types  of  power  plants  that  have  been  so  widely  utilized 
in  automobiles  and  which  have  but  slight  modifications 
to  increase  reliability  and  mechanical  strength  and  pro- 
•duce  a  reduction  in  weight.  This  class  includes  the 
vertical  engines  such  as  the  Duesenberg  and  Hall-Scott 
four-cylinder;  the  Wisconsin,  Aeromarine,  Mercedes, 
Benz,  and  Hall-Scott  six-cylinder  vertical  engines  and 
the  numerous  eight-  and  twelve-cylinder  Vee  designs  such 
as  the  Curtiss,  Renault,  Thomas-Morse,  Sturtevant,  Sun- 
beam, and  others. 


Anzani  Air-Cooled  'Engines  459 

ANZANI   ENGINES 

The  attention  of  the  mechanical  world  was  first  di- 
rected to  the  great  possibilities  of  mechanical  flight  when 
Bleriot  crossed  the  English  Channel  in  July,  1909,  in  a 
monoplane  of  his  own  design  and  construction,  having 
the  power  furnished  by  a  small  three-cylinder  air-cooled 
engine  rated  at  about  24  horse-power  and  having  cylin- 
ders 4.13  inches  bore  and  5.12  inches  stroke,  stated  to 
develop  the  power  at  about  1600  R.P.M.  and  weighing  145 
pounds.  The  arrangement  of  this  early  Anzani  engine  is 
shown  at  Fig.  190,  and  it  will  be  apparent  that  in  'the 
main,  the  lines  worked  out  in  motorcycle  practice  were 
followed  to  a  large  extent.  The  crank-case  was  of  the 
usual  vertically  divided  pattern,  the  cylinders  and  heads 
being  cast  in  one  piece  and  held  to  the  crank-case  by 
stud  bolts  passing  through  substantial  flanges  at  the 
cylinder  base.  In  order  to  utilize  but  a  single  crank-pin 
for  the  three  cylinders  it  was  necessary  to  use  two  forked 
rods  and  one  rod  of  the  conventional  type.  The  arrange- 
ment shown  at  Fig.  190,  called  for  the  use  of  counter- 
balanced flywheels  which  were  built  up  in  connection 
with  shafts  and  a  crank-pin  to  form  what  corresponds  to 
the  usual  crank-shaft  assembly. 

The  inlet  valves  were  of  the  automatic  type  so  that  a 
very  simple  valve  mechanism  consisting  only  of  the  ex- 
haust valve  push  rods  was  provided.  One  of  the  diffi- 
culties of  this  arrangement  of  cylinders  was  that  the 
impulses  are  not  evenly  spaced.  For  instance,  in  the 
forms  where  the  cylinders  were  placed  60  degrees  apart 
the  space  between  the  firing  of  the  first  cylinder  and  that 
next  in  order  was  120  degrees  crank- shaft  rotation,  after 
which  there  was  an  interval  of  300  degrees  before  the 
last  cylinder  to  fire  delivered  its  power  stroke.  In  order 
to  increase  the  power  given  by  the  simple  three-cylinder 
air-cooled  engine  a  six-cylinder  water-cooled  type,  as 
shown  at  Figs.  191  and  192,  was  devised.  This  was  prac- 
tically the  same  in  action  as  the  three-cylinder  except 


460 


Aviation  Engines 


o 
O 

faJO 

I 
I 

O 


A.G.HAGSTROM   N.Y. 


Fig.  190a. — Illustrations  Depicting  Wrong  and  Eight  Methods  of  "Swing- 
ing the  Stick"  to  Start  Airplane  Engine.  At  Top,  Poor  Position  to 
Get  Full  Throw  and  Get  Out  of  the  Way.  Below,  Correct  Position 
to  Get  Quick  Turn  Over  of  Crank-Shaft  and  Spring  Away  from 
Propeller. 

461 


462 


Aviation  Engines 


that  a  double  throw  crank-shaft  was  used  and  while  the 
explosions  were  not  evenly  spaced  the  number  of  explo- 
sions obtained  resulted  in  fairly  uniform  application  of 
power. 

The  latest  design  of  three-cylinder  Anzani  engine, 
which  is  used  to  some  extent  for  school  machines,  is 
shown  at  Fig.  193.  In  this,  the  three-cylinders  are  sym- 


Fig.  191. — The  Anzani  Six-Cylinder  Water-Cooled  Aviation  Engine. 

metrically  arranged  about  the  crank-case  or  120  degrees 
apart.  The  balance  is  greatly  improved  by  this  arrange- 
ment and  the  power  strokes  occur  at  equal  intervals  of 
240  degrees  of  crank-shaft  rotation.  This  method  of  con- 
struction is  known  as  the  Y  design.  By  grouping  two  of 
these  engines  together,  as  outlined  at  Fig.  194,  which 
gives  an  internal  view,  and  at  Fig.  195,  which  shows  the 
sectional  view,  and  using  the  ordinary  form  of  double 
throw  crank-shaft  with  crank-pins  separated  by  180  de- 
grees, a  six-cylinder  radial  engine  is  produced  which  runs 


Anzani  Aviation  Engines 


463 


very  quietly  and  furnishes  a  steady  output  of  power. 
The  peculiarity  of  the  construction  of  this  engine  is  in 
the  method  of  grouping  the  connecting  rod  about  the 
common  crank-pin  without  using  forked  rods  or  the 
"Mother  rod"  system  employed  in  the  Gnome  engines. 
In  the  Anzani  the  method  followed  is  to  provide  each 


,  Cool  ing  Water 
Outlets— 


.•Water  Jacket 


Water 
Outlet 


'*  Exhaust 
ValvQ 


Connecting-'  .XN|. 

Rods.  A^\\      A' 


Crank-Shaft"'' 


Crank  Case--' 


'•Cylinder 


^-Flywheel 


Fig.  192.— Sectional  View  of  Anzani  Six-Cylinder  Water-Cooled  Aviation 

Engine. 

connecting  rod  big  end  with  a  shoe  which  consists  of  a 
portion  of  a  hollow  cylinder  held  against  the  crank-pin 
by  split  clamping  rings.  The  dimensions  of  these  shoes 
are  so  proportioned  that  the  two  adjacent  connecting  rods 
of  a  group  of  three  will  not  come  into  contact  even  when 
the  connecting  rods  are  at  the  minimum  relative  angle. 
The  three  shoes  of  each  group  rest  upon  a  bronze  sleeve 
which  is  in  halves  and  which  surrounds  the  crank-pin 


464 


Aviation  Engines 


and  rotates  relatively  to  it  once  in  each  crank-shaft  revo- 
lution. The  collars,  which  are  of  tough  bronze,  resist  the 
inertia  forces  while  the  direct  pressure  of  the  explosions 
is  transmitted  directly  to  the  crank-pin  bushing  by  the 
shoes  at  the  big  end  of  the  connecting  rod.  The  same 


Valve 
Operating  Rod 


Intake  Pipe u-,_    ^~[= 


/Cylinder  No.  I 


<— Cylinder  hold 
down  Bolts 


Cylinder  No.  3- 

Carburetor--' 


.G.HAGSTROM  N.Y 


Fig.  193. — Three-Cylinder  Anzani  Air-Cooled  Y-Form  Engine. 

method  of  construction,  modified  to  some  extent,  is  used 
in  the  LeKhone  rotary  cylinder  engine. 

Both  cylinders  and  pistons  of  the  Anzani  engines  are 
of  cast  iron,  the  cylinders  being  provided  with  a  liberal 
number  of  cooling  flanges  which  are  cast  integrally.  A 
series  of  auxiliary  exhaust  ports  is  drilled  near  the  base 


Anzani  Engine  Construction 


465 


of  each  cylinder  so  that  a  portion  of  the  exhaust  gases 
will  flow  out  of  the  cylinder  when  the  piston  reaches  the 
end  of  its  power  stroke.  This  reduces  the  temperature 
of  the  gases  passing  around  the  exhaust  valves  and  pre- 


,'Valve 


Exhaust 

Elbow-... 


•Induction  Pipe 


Cylinder  hold 
down  Bolts -- 


Valve  Rocker — 


^•Valve  Lift  Rod 


Carburetor 


A.G.HAGSTROM   N.Y. 


Fig.   194. — Anzani  Fixed   Crank-Case    Engine   of   the   Six-Cylinder   Form 
Utilizes  Air  Cooling  Successfully. 

vents  warping  of  these  members.  Another  distinctive 
feature  of  this  engine  design  is  the  method  of  attaching 
the  Zenith  carburetor  to  an  annular  chamber  surrounding 
the  rear  portion  of  the  crank-case  from  which  the  intake 
pipes  leading  to  the  intake  valves  radiate.  The  magneto 


466 


Aviation  Engines 


is  the  usual  six-cylinder  form  having  the  armature  geared 
to  revolve  at  one  and  one-half  times  crank- shaft  speed.   . 

The  Anzani   aviation  engines   are   also  made   in  ten- 
and  twenty-cylinder  forms  as  shown  at  Fig.  196.     It  will 


Propeller^ 


Exhaust  Valve  Rocker. 


-Exhaust  Valve,  Push  Rod 


Section  PC  showing 
Construction  of 
Connecting  Rod 
Big  Ends 


'Magneto 
Magneto  Drive  Gear 


-Intake  Gas  Passage 
..-—Carburetor 

"" 'Primary  flir  Intake 


'~~~ Fuel  Pipe 
Cooled  Cylinder 


Fig.  195. — Sectional  View  Showing  Internal  Parts  of  Six-Cylinder  Anzani 
Engine,  with  Starwise  Disposition  of  Cylinders. 


467 


468 


Aviation  Engines 


be  apparent  that  in  the  ten-cylinder  form  explosions  will 
occur  every  72  degrees  of  crank-shaft  rotation,  while  in 
the  twenty-cylinder,  200  horse-power  engine  at  any  in- 


Fig.   197. — Application   of  R.   E.   P.   Five-Cylinder   Fan-Shape    Air-Cooled 
Motor  to  Early  Monoplane. 

stant  five  of  the  cylinders  are  always  working  and  ex- 
plosions are  occurring  every  36  degrees  of  crank-shaft 
rotation.  On  the  twenty-cylinder  engine,  two  carburetors 


Canton  and  Unne  Engine  469 

are  used  and  two  magnetos,  which  are  driven  at  two  and 
one-half  times  crank-shaft  speed.  The  general  cylinder 
and  valve  construction  is  practically  the  same,  as  in  the 
simpler  engines. 

CANTON   AND   UNNE   ENGINE 

This  engine,  which  has  been  devised  specially  for 
aviation  service,  is  generally  known  as  the  "Salmson" 
and  is  manufactured  in  both  France  and  Great  Britain. 
It  is  a  nine-cylinder  water-cooled  radial  engine,  the  nine- 
cylinders  being  symmetrically  disposed  around  the  crank- 
shaft while  the  nine  connecting  rods  all  operate  on  a 
comman  crank-pin  in  somewhat  the  same  manner  as  the 
rods  in  the  Gnome  motor.  The  crank-shaft  of  the  Salm- 
son engine  is  not  a  fixed  one  and  inasmuch  as  the  cylin- 
ders do  not  rotate  about  the  crank-shaft  it  is  necessary 
for  that  member  to  revolve  as  in  the  conventional  engine. 
The  stout  hollow  steel  crank-shaft  is  in  two  pieces  and 
has  a  single  throw.  The  crank-shaft  is  built  up  some- 
what the  same  as  that  of  the  Gnome  engine.  Ball  bear- 
ings are  used  throughout  this  engine  as  will  be  evident 
by  inspecting  the  sectional  view  given  at  Fig.  199.  The 
nine  steel  connecting  rods  are  machined  all  over  and  are 
fitted  at  each  end  with  bronze  bushings,  the  distance 
between  the  bearing  centers  being  about  3.25  times  crank 
length.  The  method  of  connecting  up  the  rods  to  the 
crank-pin  is  one  of  the  characteristic  features  of  this 
design.  No  "mother"  rod  as  supplied  in  the  Gnome 
engine  is  used  in  this  type  inasmuch  as  the  steel'  cage  or 
connecting  rod  carrier  is  fitted  with  symmetrically  dis- 
posed big  end  retaining  pins.  Inasmuch  as  the  carrier 
is  mounted  on  ball  bearings  some  means  must  be  pro- 
vided of  regulating  the  motion  of  the  carrier  as  if  no 
means  were  provided  the  resulting  motion  of  the  pistons 
would  be  irregular. 

The  method  by  which  the  piston  strokes  are  made  to 
occur  at  precise  intervals  involves  a  somewhat  lengthy 
and  detailed  technical  explanation.  It  is  sufficient  to  say 


470 


Aviation  Engines 


that  an  epicyclic  train  of  gears,  one  of  which  is  rigidly 
attached  to  the  crank-case  so  it  cannot  rotate  is  used, 
while  other  gears  make  a  connection  between  the  fixed 
gear  and  with  another  gear  which  is  exactly  the  same 


Fig.  198. — The  Canton  and  Unne  Nine-Cylinder  Water-Cooled  Radial 

Engine. 

size  as  the  fixed  gear  attached  to  the  crank-case  and  which 
is  formed  integrally  with  the  connecting  rod  carrier.  The 
action  of  the  gearing  is  such  that  the  cage  carrying  the 
big  end  retaining  pins  does  not  rotate  independently  of 


Canton  and  Unne  Engine 


471 


the  crank-shaft,  though,  of  course,  the  crank-shaft  or 
rather  crank-pin  bearings  must  turn  inside  of  the  big 
end  carrier  cage. 

Cylinders  of  this  engine  are  of  nickel  steel  machined 
all  over  and  carry  water-jackets  of  spun  copper  which 
are  attached  to  the  cylinders  by  brazing.  The  water 


Rocker  Lever--- 

Valve  Ro eker Support 

Valve  Stem 


How  One  Cam 
Operates  Two  Valves 


Intermediate 
Planetary  Pinions.--^ 


-^Radial  Ball 
Bearings 

sembly  Drive  Gear 


Non-Rotating 
Crank  Case 


--Equalizing 
•'     Gear     " 
Train 


--Fixed 
Equalizing 
Gear 


\?o  to  ry 
CrankShaft 


'Cam  Drive  Gear 


Crank  Shaft  Bearings 


Fig.  199. — Sectional  View  Showing  Construction  of  Canton  and  Unne 
Water-Cooled  Radial  Cylinder  Engine. 


jackets  are  corrugated  to  permit  the  cylinder  to  expand 
freely.  The  ignition  is  similar  to  that  of  the  fixed  crank 
rotating  cylinder  engine.  An  ordinary  magneto  of  the 
two  spark  type  driven  at  1%  times  crank-shaft  speed  is 
sufficient  to  ignite  the  seven-cylinder  form,  while  in  the 


472  Aviation  Engines 

nine-cylinder  engines  the  ignition  magneto  is  of  the 
"shield"  type  giving  four  sparks  per  revolution.  The 
magneto  is  driven  at  1%  times  crank-shaft  speed.  Nickel 
steel  valves  are  used  and  are  carried  in  castings  or  cages 
which  screw  into  bosses  in  the  cylinder  head.  Each 
valve  is  cam  operated  through  a  tappet,  push  rod  and 
rocker  arm,  seven  cams  being  used  on  a  seven-cylinder 
engine  and  nine  cams  on  the  nine-cylinder.  One  cam 
serves  to  open  both  valves  as  in  its  rotation  it  lifts  the 
tappets  in  succession  and  so  operates  the  exhaust  and 
inlet  valves  respectively.  This  method  of  operation  in- 
volves the  same  period  of  intake  and  exhaust.  In  nor- 
mal engine  practice  the  inlet  valve  opens  12  degrees 
late  and  closes  20  degrees  late.  The  exhaust  opens 
45  degrees  early  and  closes  6  degrees  late.  This  means 
about  188  degrees  in  the  case  of  inlet  valve  and  231  de- 
grees crank-shaft  travel  for  exhaust  valves.  In  the 
Salmson  engine,  the  exhaust  closes  and  the  inlet  opens  at 
the  outer  dead  center  and  the  exhaust  opens  and  the  inlet 
closes  at  about  the  inner  dead  center.  This  engine  is 
also  made  in  a  fourteen-cylinder  200  B.  H.  P.  design 
which  is  composed  of  two  groups  of  seven-cylinders,  and 
it  has  been  made  in  an  eighteen-cylinder  design  of  600 
horse-power.  The  nine-cylinder  130  horse-power  has  a 
cylinder  bore  of  4.73  inches  and  a  stroke  of  5.52  inches. 
Its  normal  speed  of  rotation  is  1250  E.  P.  M.  Owing  to 
the  radial  arrangement  of  the  cylinders,  the  weight  is  but 
pounds  per  B.  H.  P. 


CONSTRUCTION   OF   EARLY   GNOME    MOTOR 

•  •  •     9'-   ,  ••- 

It  cannot  be  denied  that  for  a  time  one  of  the  most 
widely  used  of  aeroplane  motors  was  the  seven-cylinder 
revolving  air-cooled  Gnome,  made  in  France.  For  a  total 
weight  of  167  pounds  this  motor  developed  45  to  47  horse- 
power at  1,000  revolutions,  being  equal  to  3.35  pounds 
per  horse-power,  and  has  proved  its  reliability  by  securing 
many  long-distance  and  endurance  records.  The  same 


473 


474  Aviation  Engines 

engineers  have  produced  a  nine-cylinder  and  by  combi- 
ning two  single  engines  a  four  teen-cylinder  revolving 
Gnome,  having  a  nominal  rating  of  100  horse-power,  with 
which  world's  speed  records  were  broken.  A  still  more 
powerful  engine  has  been  made  with  eighteen-cylinders. 
The  nine-cylinder  "monosoupape"  delivers  100  horse- 
power at  1200  K.  P.  M.,  the  engine  of  double  that  number 
of  cylinders  is  rated  at  about  180  horse-power. 

Except  in  the  number  of  cylinders  and  a  few  mechani- 
cal details  the  fourteen-cylinder  motor  is  identical  with 
the  seven-cylinder  one;  fully  three-quarters  of  the  parts 
used  by  the  assemblers  would  do  just  as  well  for  one 
motor  as  for  the  other.  Owing  to  the  greater  power  de- 
mands of  the  modern  airplane  the  smaller  sizes  of  Gnome 
engines  are  not  used  as  much  as  they  were  except  for 
school  machines.  There  is  very  little  in  this  motor  that 
is  common  to  the  standard  type  of  vertical  motorcar 
engine.  The  cylinders  are  mounted  radially  round  a  cir- 
cular crank-case;  the  crank-shaft  is  fixed,  and  the  entire 
mass  of  cylinders  and  crank-case  revolves  around  it  as 
outlined  at  Fig.  200.'  The  explosive  mixture  and  the 
lubricating  oil  are  admitted  through  the  fixed  hollow 
crank-shaft,  passed  into  the  explosion  chamber  through 
an  automatic  intake  valve  in  the  piston  head  in  the  early 
pattern,  and  the  spent  gases  exhausted  through  a  me- 
chanically operated  valve  in  the  cylinder  head.  The 
course  of  the  gases  is  practically  a  radial  one.  A  pecu- 
liarity of  the  construction  of  the  motor  is  that  nickel  steel 
is  used  throughout.  Aluminum  is  employed  for  the  two 
oil  pump  housings;  the  single  compression  ring  known 
as  the  "obdurator"  for  each  piston  is  made  of  brass; 
there  are  three  or  four  brass  bushes;  gun  metal  is  em- 
ployed for  certain  pins — the  rest  is  machined  out  of 
chrome  nickel  steel.  The  crank-case  is  practically  a  steel 
hoop,  the  depth  depending  on  whether  it  has  to  receive 
seven-  or  f ourteen-cylinders ;  it  has  seven  or  fourteen 
holes  bored  as  illustrated  on  its  circumference.  When 
fourteen  or  eighteen  cylinders  are  used  the  holes  are 


Gnome  Engine  Details  475 

bored  in  two  distinct  planes,  and  offset  in  relation  one  to 
the  other. 

The  cylinders  of  the  small  engine  which  have  a  bore 
of  4%o  inches  and  a  stroke  of  4%0  inches,  are  machined 
out  of  the  solid  bar  of  steel  until  the  thickness  of  the  walls 
is  only  1.5  millimeters — .05905  inch,  or  practically  %6  inch. 
Each  one  has  twenty-two  fins  which  gradually  taper  down 
as  the  region  of  greatest  pressure  is  departed  from.  In 
addition  to  carrying  away  heat,  the  fins  assist  in  strength- 
ening the  walls  of  the  cylinder.  The  barrel  of  the  cylin- 
der is  slipped  into  the  hole  bored  for  it  on  the  circum- 
ference of  the  crank-case  and  secured  by  a  locking  member 
in  the  nature  of  a  stout  compression  ring,  sprung  onto  a 
groove  on  the  base  of  the  cylinder  within  the  crank  cham- 
ber. On  each  lateral  face  of  the  crank  chamber  are  seven 
holes,  drilled  right  through  the  chamber  parallel  with  the 
crank-shaft.  Each  one  of  these  holes  receives  a  stout 
locking-pin  of  such  a  diameter  that  it  presses  against 
the  split  rings  of  two  adjacent  cylinders;  in  addition 
each  cylinder  is  fitted  with  a  key- way.  This  construction 
is  not  always  followed,  some  of  the  early  Gnome  engines 
using  the  same  system  of  cylinder  retention  as  used  on 
the  latest  "monosoupape"  pattern. 

The  exhaust  valve  is  mounted  in  the  cylinder  head, 
Fig.  201,  its  seating  being  screwed  in  by  means  of  a 
special  box  spanner.  On  the  fourteen-cylinder  model  the 
valve  is  operated  directly  by  an  overhead  rocker  arm 
with  a  gun  metal  rocker  at  its  extremity  coming  in  con- 
tact with  the  extremity  of  the  valve  stem.  As  in  standard 
motor  car  practice,  the  valve  is  opened  under  the  lift  of 
the  vertical  push  rod,  actuated  by  the  cam.  The  distinc- 
tive feature  is  the  use  of  a  four-blade  leaf  spring  with 
a  forked  end  encircling  the  valve  stems  and  pressing 
against  a  collar  on  its  extremity.  On  the  seven-cylinder 
model  the  movement  is  reversed,  the  valve  being  opened 
on  the  downward  pull  of  the  push  rod,  this  lifting  the 
outer  extremity  of  the  main  rocker  arm,  wrhich  tips  a 
secondary  and  smaller  rocker  arm  in  direct  contact  with 


476 


Aviation  Engines 


the  extremity  of  the  valve  stem.  The  springs  are  the 
same  in  each  case.  The  two  types  are  compared  at  A 
and  B,  Fig.  202. 


Exhaust  Valve  Spring, 


..--• Valve  Depressing 
Rocker 


.Exhaust  Valve 


Spark 
'Plug 


^.-Cooling 
•  Flanges 


Exhaust  Valve-' 

Electrodes— -~- 
slnlet  Valve 


•-Piston 
Rings 


•yU.-*  Cylinder 


^  Valve  Actuating  Push  Rod 


Fig.    201. — Sectional   View   of   Early   Type   Gnome    Cylinder    and   Piston 
Showing  Construction  and  Application  of  Inlet  and  Exhaust  Valves. 

The  pistons,  like  the  cylinders,  are  machined  out  of 
the  solid  bar  of  nickel  steel,  and  have  a  portion  of  their 
wall  cut  away,  so  that  the  two  adjacent  ones  will  not 
come  together  at  the  extremity  of  their  stroke.  The  head 


.5? 

PH 


477 


478  Aviation  Engines 

• 

of  the  piston  is  slightly  reduced  in  diameter  and  is  pro- 
vided with  a  groove  into  which  is  fitted  a  very  light 
L-section  brass  split  ring;  back  of  this  ring  and  carried 
within  the  groove  is  sprung  a  light  steel  compression 
ring,  serving  to  keep  the  brass  ring  in  expansion.  As 
already  mentioned,  the  intake  valves  are  automatic,  and 
are  mounted  in  the  head  of  the  piston  as  outlined  at  Fig. 
202,  C.  The  valve  seating  is  in  halves,  the  lower  portion 
being  made  to  receive  the  wrist-pin  and  connecting  rod, 
and  the  upper  portion,  carrying  the  valve,  being  screwed 
into  it.  The  spring  is  composed  of  four  flat  blades,  with 
the  hollowed  stem  of  the  automatic  valve  passing  through 
their  center  and  their  two  extremities  attached  to  small 
levers  calculated  to  give  balance  against  centrifugal  force. 
The  springs  are  naturally  within  the  piston,  and  are  lubri- 
cated by  splash  from  the  crank  chamber.  They  are  of 
a  delicate  construction,  for  it  is  necessary  that  they  shall 
be  accurately  balanced  so  as  to  have  no  tendency  to  fly 
open  under  the  action  of  centrifugal  force.  The  intake 
valve  is  withdrawn  by  the  use  of  special  tools  through  the 
cylinder  head,  the  exhaust  valve  being  first  dismounted. 
The  fourteen-cylinder  motor  shown  at  Fig.  203,  has  a 
two-throw  crank-shaft  with  the  throws  placed  at  180  de- 
grees, each  one  receiving  seven  connecting  rods.  The 
parts  are  the  same  as  for  the  seven-cylinder  motor,  the 
larger  one  consisting  of  two  groups  placed  side  by  side. 
For  each  group  of  seven-cylinders  there  is  one  main  con- 
necting rod,  together  with  six  auxiliary  rods.  The  main 
connecting  rod,  which,  like  the  others,  is  of  H  section,  has 
machined  with  it  two  L-section  rings  bored  with  six  holes 
— 51%  degrees  apart  to  take  the  six  other  connecting 
rods.  The  cage  of  the  main  connecting  rod  carries  two 
ball  races,  one  on  either  side,  fitting  onto  the  crank-pin 
and  receiving  the  thrust  of  the  seven  connecting  rods. 
The  auxiliary  connecting  rods  are  secured  in  position  in 
each  case  by  a  hollow  steel  pin  passing  through  the  two 
rings.  It  is  evident  that  there  is  a  slightly  greater  angu- 
larity for  the  six  shorter  rods,  known  as  auxiliary  con- 


Gnome  Engine  Details 


479 


480  Aviation  Engines 

necting  rods,  than  for  the  longer  main  rods ;  this  does  not 
appear  to  have  any  influence  on  the  running  of  the  motor. 

Coming  to  the  manner  in  which  the  earliest  design  ex- 
haust valves  are  operated  on  the  old  style  motor,  this  at 
first  sight  appears  to  be  one  of  the  most  complicated 
parts  of  the  motor,  probably  because  it  is  one  in  which 
standard  practice  is  most  widely  departed  from.  Within 
the  cylindrical  casing  bolted  to  the  rear  face  of  the  crank- 
case  are  seven,  thin  flat-faced  steel  rings,  forming  female 
cams.  Across  a  diameter  of  each  ring  is  a  pair  of  pro- 
jecting rods  fitting  in  brass  guides  and  having  their 
extremities  terminating  in  a  knuckle  eye  receiving  the 
adjustable  push  rods  operating  the  overhead  rocker  arms 
of  the  exhaust  valve.  The  guides  are  not  all  in  the  same 
plane,  the  difference  >  being  equal  to  the  thickness  of  the 
steel  rings,  the  total  thickness  being  practically  2  inches. 
Within  the  female  cams  is  a  group  of  seven  male  cams 
of  the  same  total  thickness  as  the  former  and  rotating 
within  them.  As  the  boss  of  the  male  cam  comes  into 
contact  with  the  flattened  portion  of  the  ring  forming 
the  female  cam,  the  arm  is  pushed  outward  and  the  ex- 
haust valve  opened  through  the  medium  of  the  push-rod 
and  overhead  rocker.  This  construction  was  afterwards 
changed  to  seven  male  cams  and  simple  valve  operating 
plunger  and  roller  cam  followers  as  shown  at  Fig.  204. 

On  the  face  of  the  crank-case  of  the  fourteen-cylinder 
motor  opposite  to  the  valve  mechanism  is  a  bolted-on  end 
plate,  carrying  a  pinion  for  driving  the  two  magnetos 
and  the  two  oil  pumps,  and  having  bolted  to  it  the  dis- 
tributor for  the  high-tension  current.  Each  group  of 
seven-cylinders  has  its  own  magneto  and  lubricating 
pump.  The  two  magnetos  and  the  two  pumps  are  mounted 
on  the  fixed  platform  carrying  the  stationary  crank-shaft, 
being  driven  by  the  pinion  on  the  revolving  crank  cham- 
ber. The  magnetos  are  geared  up  in  the  proportion  of 
4  to  7.  Mounted  on  the  end  plate  back  of  the  driving 
pinion  are  the  two  high-tension  distributor  plates,  each 
one  with  seven  brass  segments  let  into  it  and  connection 


Gnome  Engine  Details 


481 


made  to  the  plugs  by  means  of  plain  brass  wire.  The 
wire  passes  through  a  hole  in  the  plug  and  is  then 
wrapped  round  itself,  giving  a  loose  connection. 


Revolving          Carri 

Planetary 

Pinions 


Hon- 
Rotative 
Timing  K 
Gear 


Ball 
Bearing 


-_ Valve' Actuating  Tube 

\ 

^1     ff-Valve  Plunger  Guide 
^,f" Valve  Plunger 

Roller 
Bearing 


,'Fixed  Crank-Shaft  End 


>  Crank- Sh  aft 
Tie  Bolt 


Revolving  Planetary 
Pinions 


**  Planetary  Pinion  Stud 


Cam  Case  Flange' 


Fig.  204. — Cam  and  Cam-Gear  Case  of  the  Gnome  Seven-Cylinder 
Revolving  Engine. 


482 


Aviation  Engines 


A  good  many  people  doubtless  wonder  why  rotary  en- 
gines are  usually  provided  with  an  odd  number  of  cylin- 
ders in  preference  to  an  even  number.  It  is  a  matter  of 
even  torque,  as  can  easily  be  understood  from  the  accom- 
panying diagram.  Fig.  205,  A,  represents  a  six-cylinder 
rotary  engine,  the  radial  lines  indicating  the  cylinders. 
It  is  possible  to  fire  the  charges  in  two  ways,  firstly,  in 
rotation, -1,  2,  3,  4,  5,  6,  thus  having  six  impulses  in  one 
revolution  and  none  in  the  next;  or  alternately,  1,  3,  5,  2, 
4,  6,  in  which  case  the  engine  will  have  turned  through 


Fig.  205. — Diagrams  Showing  Why  An  Odd  Number  of  Cylinders  is  Best 
for  Eotary  Cylinder  Motors. 

an  equal  number  of  degrees  between  impulses  1  and  3, 
and  3  and  5,  but  a  greater  number  between  5  and  2,  even 
again  between  2  and  4,  4  and  6,  and  a  less  number  be- 
tween 6  and  1,  as  will  be  clearly  seen  on  reference  to  the 
diagram.  Turning  to  Fig.  205,  B,  which  represents  a 
seven-cylinder  engine.  If  the  cylinders  fire  alternately 
it  is  obvious  that  the  engine  turns  through  an  equal 
number  of  degrees  between  each  impulse,  thus,  1,  3,  5,  7, 
2,  4,  6,  1,  3,  etc.  Thus  supposing  the  engine  to  be  revolv- 
ing, the  explosion  takes  place  as  each  alternate  cylinder 
passes,  for  instance,  the  point  1  on  the  diagram,  and  the 
ignition  is  actually  operated  in  this  way  by  a  single 
contact. 


Gnome  Engine  Details 


483 


The  crank-shaft  of  the  Gnome,  as  already  explained, 
is  fixed  and  hollow.  For  the  seven-  and  nine-cylinder 
motors  it  has  a  single  throw,  and  for  the  fourteen-  and 
eighteen-cylinder  models  has 'two  throws  at  180  degrees. 
It  is  of  the  built-up  type,  this  being  necessary  on  account 


/ThroHle  Lever 


.Crctnk-Shaft  End 


Tig.   206. — Simple   Carburetor  Used  On   Early  Gnome   Engines   Attached 
to  Fixed  Crank-Shaft  End. 

of  the  distinctive  mounting  of  the  connecting  rods.  The 
carburetor  shown  at  Fig.  206  is  mounted  at  one  end  of 
.  the  stationary  crank-shaft,  and  the  mixture  is  drawn  in 
through  a  valve  in  the  piston  as  already  explained.  There 
is  neither  float  chamber  nor  jet.  In  many  of  the  tests 
made  at  the  factory  it  is  said  the  motor  will  run  with  the 
extremity  of  the  gasoline  pipe  pushed  into  the  hollow 


484 


Aviation  Engines 


crank-shaft,  speed  being  regulated  entirely  by  increasing 
or  decreasing  the  flow  through  the  shut-off  valve  in  the 
base  of  the  tank.  Even  under  these  conditions  the  motor 
has  been  throttled  down  to 'run  at  350  revolutions  with- 
out misfiring.  Its  normal  speed  is  1,000  to  1,200  revolu- 
tions a  minute.  Castor  oil  is  used  for  lubricating  the 
engine,  the  oil  being  injected  into  the  hollow  crank- shaft 


.Ball  Bearings^ 


•Pump  Drive  Bear 


—        Cam—\, 


.'Worm 


''-Cam  Shaft 
Drive  Worm 
Gear 


Pump 
Cylinder"' 


Pump  Plunger'' 


'Plunger  Return 
Springs 


Valve 
Plunger 


Oil  Pipe 


Fig.  207. — Sectional  Views  of  the  Gnome  Oil  Pump. 

through  slight-feed  fittings  by  a  mechanically  operated 
pump  which  is  clearly  shown  in  sectional  diagrams  at 
Fig.  207. 

The  Gnome  is  a  considerable  consumer  of  lubricant, 
the  makers'  estimate  being  7  pints  an  hour  for  the  100 
horse-power  motor;  but  in  practice  this  is  largely  ex- 
ceeded. The  gasoline  consumption  is  given  as  300  to  350 
grammes  per  horse-power.  The  total  weight  of  the  four- 
teen-cylinder  motor  is  220  pounds  without  fuel  or  lubri- 


Gnome  Engine  Details 


485 


eating  oil.  Its  full  power  is  developed  at  1,200  revolu- 
tions, and  at  this  speed  about  9  horse-power  is  lost  in 
overcoming  air  resistance  to  cylinder  rotation. 

While  the  Gnome  engine  has  many  advantages,  on  the 
other  hand,  the  head  resistance  offered  by  a  motor  of  this 


Current  Supply  Brush 


.-—Secondary  Wire  to  Plug 


Spark  Plug 


"Magneto 
Collector  Ring 


Ma  gnet- 


Fig.  208. — Simplified  Diagram  Showing  Gnome  Motor  Magneto  Ignition 

System. 

type  is  considerable ;  there  is  a  large  waste  of  lubricating 
oil  due  to  the  centrifugal  force  which  tends  to  throw  the 
oil  away  from  the  cylinders;  the  gyroscopic  effect  of 
the  rotary  motor  is  detrimental  to  the  best  working  of  the 
aeroplane,  and  moreover  it  requires  about  seven  per  cent, 
of  the  total  power  developed  by  the  motor  to  drive  the 
revolving  cylinders  around  the  shaft.  Of  necessity,  the 


486  Aviation  Engines 

compression  of  this  type  of  motor  is  rather  low,  and  an 
additional  disadvantage  manifests  itself  in  the  fact  that 
there  is  as  yet  no  satisfactory  way  of  muffling  the  rotary 
type  of  motor. 

GNOME  "MONOSOUPAPE"  TYPE 

The  latest  type  of  Gnome  engine  is  known  as  the 
"monosoupape"  type  because  but  one  valve  is  used  in 
the  cylinder  head,  the  inlet -valve  in  the  piston  being  dis- 
pensed with  on  account  of  the  trouble  caused  by  that 
member  on  earlier  engines.  The  construction  of  this 
latest  type  follows  the  lines  established  in  the  earlier 
designs  to  some  extent  and  it  differs  only  in  the  method 
of  charging.  The  very  rich  mixture  of  gas  and  air  is 
forced  into  the  crank-case  through  the  jet  inside  the 
crank- shaft,  and  enters  the  cylinder  when  the  piston  is 
at  its  lowest  position,  through  the  half-round  openings 
in  the  guiding  flange  and  the  small  holes  or  ports  ma- 
chined in  the  cylinder  and  clearly  shown  at  Fig.  210. 
The  returning  piston  covers  the  port,  and  the  gas  is  com- 
pressed and  fired  in  the  usual  way.  The  exhaust  is 
through  a  large  single  valve  in  the  cylinder  head,  which 
gives  rise  to  the  name  "monosoupape,"  or  single-valve 
motor,  and  this  valve  also  remains  open  a  portion  of  the 
intake  stroke  to  admit  air  into  the  cylinder  and  dilute 
the  rich  gas  forced  in  from  the  crank-case  interior. 
Aviators  who  have  used  the  early  form  of  Gnome  say 
that  the  inlet  valve  in  the  piston  type  was  prone  to  catch 
on  fire  if  any  valve  defect  materialized,  but  the  "monosou- 
pape"  pattern  is  said  to  be  nearly  free  of  this  danger. 
The  bore  of  the  100  horse-power  nine-cylinder  engine  is 
110  mm.,  the  piston  stroke  150  mm.  Extremely  careful 
machine  work  and  fitting  is  necessary.  In  many  parts, 
tolerances  of  less  than  .0004"  (four  ten  thousandths  of 
an  inch)  are  all  that  are  allowed.  This  is  about  one- 
sixth  the  thickness  of  the  average  human  hair,  and  in 
other  parts  the  size  must  be  absolutely  standard,  no 
appreciable  variation  being  allowable.  The  manufacture 


Gnome  Monosoupape  Engine 


487 


of  this  engine  establishes  new  mechanical  standards  of 
engine  production  in  this  country.  Much  machine  work 
is  needed  in  producing  the  finished  components  from  the 
bar  and  forging. 

The  cylinders,  for  example,  are  machined  from  6  inch 
solid  steel  bars,  which  are  sawed  into  blanks  11  inches 


Fig.  209. — The  G.  V.  Gnome  "Monosoupape"  Nine-Cylinder  Eotary  Engine 
Mounted  on  Testing  Stand. 

in  length  and  weighing  about  97  pounds.  The  first  opera- 
tion is  to  drill  a  2M.6  inch  hole  through  the  center  of  the 
block.  A  heavy-duty  drilling  machine  performs  this 


488 


Aviation  Engines 


Gnome  Monosoupape  Engine  489 

work,  then  the  block  goes  to  the  lathe  for  further  opera- 
tions. Fig.  211  shows  six  stages  of  the  progress  of  a 
cylinder,  a  few  of  the  intermediate  steps  being  omitted. 


Fig.  211. — How  a  Gnome  Cylinder  is  Reduced  from  Solid   Chunk   of  Steel 
Weighing  97   Pounds  to  Finished  Cylinder  Weighing  5y2  Pounds. 

These  give,  however,  a  good  idea  of  the  work  done.  The 
turning  of  the  gills,  or  cooling  flanges,  is  a  difficult  propo- 
sition, owing  to  the  depth  of  the  cut  and  the  thin  metal 
that  forms  the  gills.  This  operation  requires  the  utmost 
care  of  tools  and  the  use  of  a  good  lubricant  to  prevent 


490  Aviation  Engines 

the  metal  from  tearing  as  the  tools  approach  their  full 
depth.  These  gills  are  only  0.6  mm.,  or  0.0237  in.,  thick 
at  the  top,  tapering  to  a  thickness  of  1.4  mm.  (0.0553  in.) 
at  the  base,  and  are  16  mm.  (0.632  in.)  deep.  When  the 
machine  work  is  completed  the  cylinder  weighs  but  5% 
pounds. 


GNOME  FUEL  SYSTEM,  IGNITION  AND  LUBRICATION 

The  following  description  of  the  fuel  supply,  ignition 
and  oiling  of  the  "monosoupape,"  or  single  valve  Gnome, 
is  taken  from  "The  Automobile. " 

Gasoline  is  fed  to  the  engine  by  means  of  air  pressure 
at  5  pounds  per  sq.  in.,  which  is  produced  by  the  air 
pump  on  the  engine  clearly  shown  at  Fig.  210.  A  pres- 
sure gauge  convenient  to  the  operator  indicates  this  pres- 
sure, and  a  valve  enables  the  operator  to  control  it.  No 
carburetor  is  used.  The  gasoline  flows  from  the  tank 
through  a  shut-off  valve  near  the  operator  and  through 
a  tube  leading  through  the  hollow  crank- shaft  to  a  spray 
nozzle  located  in  the  crank-case.  There  is  no  throttle 
valve,  and  as  each  cylinder  always  receives  the  same 
amount  of  air  as  long  as  the  atmospheric  pressure  is  the 
same,  the  output  cannot  be  varied  by  reducing  the  fuel 
supply,  except  within  narrow  limits.  A  fuel  capacity  of 
65  gallons  is  provided.  The  fuel  consumption  is  at  the 
rate  of  12  U.  S.  gallons  per  hour. 

The  high-tension  magnetos,  with  double  cam  or  two 
break  per  revolution  interrupter,  is  located  on  the  thrust 
plate  in  an  inverted  position,  and  is  driven  at  such  a 
speed  as  to  produce  nine  sparks  for  every  two  revolu- 
tions; that  is,  at  2i/4  times  engine  speed.  A  Splitdorf 
magneto  is  fitted.  There  is  no  distributor  on  the  mag- 
neto. The  high-tension  collector  brush  of  the  magneto 
is  connected  to  a  distributor  brush  holder  carried  in  the 
bearer  plate  of  the  engine.  The  brush  in  this  brush 
holder  is  pressed  against  a  distributor  ring  of  insulating 
material  molded  in  position  in  the  web  of  a  gear  wheel 


Gnome  Monosoupape  Engine  491 

keyed  to  the  thrust  plate,  which  gear  serves  also  for 
starting  the  engine  by  hand.  Molded  in  this  ring  of  in- 
sulating material  are  nine  brass  contact  sectors,  connect- 
ing with  contact  screws  at  the  back  side  of  the  gear, 
from  which  bare  wires  connect  to  the  spark-plugs.  The 
distributor  revolves  at  engine  speed,  instead  of  at  half 
engine  speed  as  on  ordinary  engines,  and  the  distributor 
brush  is  brought  into  electrical  connection  with  each 


Fig.  212. — The  Gnome  Engine  Cam-Gear  Case,  a  Fine  Example  of  Accurate 

Machine  Work. 

spark-plug  every  time  the  piston  in  the  cylinder  in  which 
this  spark-plug  is  located  approaches  the  outer  dead 
center.  However,  on  the  exhaust  stroke  no  spark  is  being 
generated  in  the  magneto,  hence  none  is  produced  at  the 
spark-plug. 

Ordinarily  the  engine  is  started  by  turning  on  the 
propeller,  but  for  emergency  purposes  as  in  seaplanes  or 
for  a  quick  "get  away"  if  landing  inadvertently  in 
enemy  territory,  a  hand  starting  crank  is  provided.  This 
is  supported  in  bearings  secured  to  the  pressed  steel 
carriers  of  the  engine  and  is  provided  with  a  universal 


492 


Aviation  Engines 


joint  between  the  two  supports  so  as  to  prevent  binding 
of  the  crank  in  the  bearings  due  to  possible  distortion 
of  the  supports.  The  gear  on  this  starting  crank  and  the 
one  on  the  thrust  plate  with  which  it  meshes  are  cut 


Fig.  213. — G.  V.  Gnome  "Monospupape,"  with  Cam-Case  Cover  Removed  to 
Show  Cams  and  Valve-Operating  Plungers  with  Roller  Cam  Followers. 

with  helical  teeth  of  such  hand  that  the  starting  pinion 
is  thrown  out  of  mesh  as  soon  as  the  engine  picks  up  its 
cycle.  A  coiled  spring  surrounds  part  of  the  shaft  of  the 
starting  crank  and  holds  it  out  of  gear  when  not  in  use. 
Lubricating  oil  is  carried  in  a  tank  of  25  gallon  ca- 
pacity, and  if  this  tank  has  to  be  placed  in  a  low  position 


German  Gnome  Type  Engine  493 

it  is  connected  with  the  air-pressure  line,  so  that  the 
suction  of  the  oil  pump  is  not  depended  upon  to  get  the 
oil  to  the  pump.  From  the  bottom  of  the  oil  tank  a  pipe 
leads  to  the  pump  inlet.  There  are  two  outlets  from  the 
pump,  each  entering  the  hollow  crank-shaft,  and  there  is 
a  branch  from  each  outlet  pipe  to  a  circulation  indicator 
convenient  to  the  operator.  One  of  the  oil  leads  feeds 
to  the  housing  in  the  thrust  plate  containing  the  two  rear 
ball  bearings,  and  the  other  lead  feeds  through  the  crank- 
pin  to  the  cams,  as  already  explained. 

Owing  to  the  effect  of  centrifugal  force  and  the  fact 
that  the  oil  is  not  used  over  again,  the  oil  consumption 
of  a  revolving  cylinder  engine; is  considerably  higher  than 
that  of  a  stationary  cylinder  engine.  Fuel  consumption 
is  also  somewhat  higher,  and  for  this  reason  the  revolv- 
ing cylinder  engine  is  not  so  well  suited  for  types  of  air- 
planes designed  for  long  trips,  as  the  increased  weight 
of  supplies  required  for  such  trips,  as  compared  with 
stationary  cylinder  type  motors,  more  than  offsets  the 
high  weight  efficiency  of  the  engine  itself.  But  for  short 
trips,  and  especially  where  high  speed  is  required,  as  in 
single  seated  scout  and  battle  planes  or  "avious  de 
chasse,"  as  the  French  say,  the  revolving  cylinder  engine 
has  the  advantage.  The  oil  consumption  of  the  Gnome 
engine  is  as  high  as  2.4  gallon  per  hour.  Castor  oil  is 
used  for  lubrication  because  it  is  not  cut  by  the  gasoline 
mist  present  in  the  engine  interior  as  an  oil  of  mineral 
derivation  would  be. 


GEKMAN  "QNOME"  TYPE 


A  German  adaptation  of  the  Gnome  design  is  shown 
at  Fig.  214.  This  is  known  as  the  Bayerischen  Motoren 
Gesellshaft  engine  and  the  type  shown  is  an  early  design 
rated  at  50  horse-power.  The  bore  is  110  mm.,  the  stroke 
is  120  mm.,  and  it  is  designed  to  run  at  a  speed  of  1,200 
K.  P.  M.  It  is  somewhat  similar  in  design  to  the  early 
Gnome  "valve-in-piston"  design  except  that  two  valves 


494 


Aviation  Engines 


§ 


M 


s 


bb 
FH 


Le  Rhone  Rotary  Motor  495 

are  carried  in  the  piston  top  instead  of  one.  The  valve 
operating  arrangement  is  different  also,  as  a  single  four 
point  cam  is  used  to  operate  the  seven  exhaust  valves. 
It  is  driven  by  epicyclic  gearing,  the  cam  being  driven  by 
an  internal  gear  machined  integrally  with  it,  the  cam 
being  turned  at  %  times  the  engine  speed.  Another 
feature  is  the  method  of  holding  the  cylinders  on  the 
crank-case.  The  cylinder  is  provided  with  a  flange  that 
registers  with  a  corresponding  member  of  the  same  diam- 
eter on  the  crank-case.  A  U  section,  split  clamping  ring 
is  bolted  in  place  as  shown,  this  holding  both  flanges 
firmly  together  and  keeping  the  cylinder  firmly  seated 
against  the  crank-case  flange.  The  "monosoupape"  type 
has  also  been  copied  and  has  received  some  application 
in  Germany,  but  the  most  successful  German  airplanes 
are  powered  with  six-cylinder  vertical  engines  such  as 
the  Benz  and  Mercedes. 


THE   LE   RHONE    MOTOR 

The  Le  Ehone  motor  is  a  radial  revolving  cylinder 
engine  that  has  many  of  the  principles  which  are  incor- 
porated in  the  Gnome  but  which  are  considered  to  be  an 
improvement  by  many  foreign  aviators.  Instead  of  having 
but  one  valve  in  the  cylinder  head,  as  the  latest  type 
"monosoupape"  Gnome  has,  the  Le  Rhone  has  two  valves, 
one  for  intake  and  one  for  exhaust  in  each .  cylinder.  By 
an  ingenious  rocker  arm  and  tappet  rod  arrangement 
it  is  possible  to  operate  both  valves  with  a  single  push 
rod.  Inlet  pipes  communicate  with  the  crank-case  at  one 
end  and  direct  the  fresh  gas  to  the  inlet  valve  cage  at  the 
other.  Another  peculiarity  in  the  design  is  the  method 
of  holding  the  cylinders  in  place.  Instead  of  having  a 
vertically  divided  crank-case  as  the  Gnome  engine  has 
and  clamping  both  valves  of  the  case  around  the  cylin- 
ders, the  crank-case  of  the  Le  Rhone  engine  is  in  the 
form  of  a  cylinder  having  nine  bosses  provided  with 
threaded  openings  into  which  the  cylinders  are  screwed. 


496 


Aviation  Engines 


A  thread  is  provided  at  the  base  of  each  cylinder  and 
when  the  cylinder  has  been  screwed  down  the  proper 
amount  it  is  prevented  from  further  rotation  about  its 
own  axis  by  a  substantial  lock  nut  which  screws  down 


Fig.  215. — Nine-Cylinder  Revolving  Le  Rhone  Type  Aviation  Engine. 

against  the  threaded  boss  on  the  crank-case.  The  ex- 
ternal appearance  of  the  Le  Ehone  type  motor  is  clearly 
shown  at  Fig.  215,  while  the  general  features  of  con- 
struction, are  clearly  outlined  in  the  sectional  views  given 
at  Figs.  216  and  217. 


497 


498 


Aviation  Engines 


The  two  main  peculiarities  of  this  motor  are  the 
method  of  valve  actuation  by  two  large  cams  and  the 
distinctive  crank-shaft  and  connecting  rod  big  end  con- 
struction. The  connecting  rods  are  provided  with  "feet" 
or  shoes  on  the  end  which  fit  into  grooves  lined  with 
bearing  metal  which  are  machined  into  crank  discs 


Piston. 
Cylinder 


'--Ball  Bearing  RockerShaft 
=.— Valve  Operating  Rod 

.-Operating  Rod  Plunger 

f.~  Ignition  Distributor 

.-•Current  Supply  Brush 
Oil 


<  J 

"Anchorage  Plates-'' 


Fixed 
Crank-Shaft- 


Rotary  Crank  Case  — _._ 


~-  Ball  Bearing 


Fig.  217. — Side  Sectional  View  of  I*e  Rhone  Aviation  Engine. 

revolving  on  ball  bearings  and  which  are  held  together  so 
that  the  connecting  rod  big  ends  are  sandwiched  between 
them  by  clamping  screws.  This  construction  is  a  modifi- 
cation of  that  used  on  the  Anzani  six-cylinder  radial 
engine.  There  are  three  grooves  machined  in  each  crank 
disc  and  three  connecting  rod  big  ends  fun  in  each  pair 
of  grooves.  The  details  of  this  construction  can  be  readily 
ascertained  by  reference  to  explanatory  diagrams  at 
Figs.  218  and  219,  A.  Three  of  the  rods  which  work 


Le  Rhone  Rotary  Motor 


499 


in  the  groove  nearest  the  crank-pin  are  provided  with 
short  shoes  as  shown  at  Fig.  219,  B.  The  short  shoes 
are  used  on  the  rods  employed  in  cylinders  number  1, 
4,  and  7.  The  set  of  connecting  rods  that  work  in  the 
central  grooves  are  provided  with  medium-length  shoes 


-Piston 


Valve 
Rocker 


Exhaust 
Valve 


Induction  Pipe, 


•'r '      ^V    t,-'A  ir  Co  o  I  in  g  Fla  ngfes 


Air  Cooled  / 
Cylinder--' 


Threads  fo 

hold  Cylinder          ' 


Crank  Case''' 


•Connecting 
Rod 


..'Connecting  Rod 
and  Crankshaft 
Assembly 


Valve  liff  Rods 


Fig.  218. — View  Showing  Le  Rhone  Valve  Action  and  Connecting  Rod 
Big  End  Arrangement. 

and  actuate  the  pistons  in  cylinders  numbers  3,  6,  and  9. 
The  three  rods  that  work  in  the  outside  grooves  have  still 
longer  shoes  and  are  employed  in  cylinders  numbers  2, 
5,  and  8.  The  peculiar  profile  of  the  inlet  and  exhaust 
cam  plates  are  shown  at  C,  Fig.  219,  while  the  construc- 
tion of  the  wrist-pin,  wrist-pin  bushing  and  piston  are 
clearly  outlined  at  the  sectional  view  at  E.  The  method 


500 


Aviation  Engines 


of  valve  actuation  is  clearly  outlined  at  Fig.  220,  which 
shows  an  end  section  through  the  cam  case  and  also 
a  partial  side  elevation  showing  one  of  the  valve  operating 
levers  which  is  fulcrumed  at  a  central  point  and  which 


Short  Rod  End  Feet        Medium  Rod  End  Feet 


on#l-4-7 


on*3-6-9 


Diagram  Showing  Connecting 
Rod  Assembly 


Lonq  Rod  End  Feet 

on*Z-5-8 

Arrangement  of  Curved  Bearingson 
Connecting  Rod  Ends 


i — /-•   C 


Piston  .. 


Wrist  Pin.-' 


Into  ke  Cam 


Fig.  219. — Diagrams  Showing  Important  Components  of  Le  Rhone  Motor. 

has  a  roller  at  one  end  bearing  on  one  cam  while  the 
roller  or  cam  follower  at  the  other  end  bears  on  the  other 
cam.  The  valve  rocker  arm  actuating  rod  is,  of  course, 
operated  by  this  simple  lever  and  is  attached  to  it  in 
such  a  way  that  it  can  be  pulled  down  to. depress  the 
inlet  valve  and  pushed  up  to  open  the  exhaust  valve. 


Le  Rhone  Engine  D.etails 


501 


A  carburetor  of  peculiar  construction  is  employed  in 
the  Le  Khone  engine,  this  being  a  very  simple  type  as 
outlined  at  Fig.  221.  It  is  attached  to  the  threaded  end 
of  the  hollow  crank-shaft  by  a  right  and  left  coupling. 


Rocker  Shaft  Actuator.^ 
Rocker'Shaff  Bearing-''.'"", 
Valve  Rocker—-"' 

Exhaust  Valve  -^ 


Valve  Actuating  Rod  - 


Air  Cooled 

Cylinder--: 


.Inlet- 
Valve 


•  Cam  Drive  Gear  Internal 


mmnX 


Fixed 
CrankShaft 


Cam 
Drive 
Pinion- 


Internal 
Pinion 


^Cam  Plate  Supporting 
Ball  Bearings 


\ 


^'Internal  Pinion 
'Internal  Gear 


Fig.  220. — How  the  Cams  of  the  Le  Rhone  Motor  Can  Operate  Two  Valves 
with  a  Single  Push  Bod. 


502 


Aviation  Engines 


The  fuel  is  pumped  to  the  spray  nozzle,  the  opening  in 
which  is  controlled  by  a  fuel  regulating  needle  having 
a  long  taper  which  is  lifted  out  of  the  jet  opening  when 
the  air-regulating  slide  is  moved.  The  amount  of  fuel 
supplied  the  carburetor  is  controlled  by  a  special  needle 
valve  fitting  which  combines  a  filter  screen  and  which  is 
shown  at  B.  In  regulating  the  speed  of  the  Le  Ehone 


Slide  Operating. 
Link 


Regulating  Slide 
Air  Screen  -x 


Fuel  Control 
Bell  Crank .._ 


Carburetor 
.'Right  and 
;    Left  Coupling 


-Needle  Seating 
Spring 


.-Link 

~' .-  Valve  Stem 
'"'  -.Stuffing-Box 

\. ---Packing 


'-Fuel  Intake 


' Fuel  Feed 

^Regulating 
Needle 


'Air  Entrance 


Fuel  Entrance- 

A 


\  *Spray  Nozzle 

^•Fuel  Regulating 
Needle 


^"Filter  Screen 

B 


Fig.  221. — The  Le  Ehone  Carburetor  at  A  and  Fuel  Supply  Regulating 

Device  at  B. 


engine,  there  are  two  possible  means  of  controlling  the 
mixture,  one  by  altering  the  position  of  the  air-regulating 
slide,  which  also  works  the  metering  needle  in  the  jet,  and 
the  other  by  controlling  the  amount  of  fuel  supplied  to 
the  spray  nozzle  through  the  special  fitting  provided  for 
that  purpose. 

In  considering  the  action  of  this  engine  one  can  refer 
to  Fig.  222.  The  crank  0.  M.  is  fixed,  while  the  cylinders 
can  turn  about  the  crank- shaft  center  0  and  the  piston 


Le  Rhone  Engine  Action 


503 


turns  around  the  crank-pin  M,  because  of  the  eccentricity 
of  the  centers  of  rotation  the  piston  will  reciprocate  in 
the  cylinders.  This  distance  is  at  its  maximum  when 
the  cylinder  is  above  0  and  at  a  minimum  when  it  is 
above  M,  and  the  difference  between  these  two  positions 
is  equal  to  the  stroke,  which  is  twice  the  distance  of  the 
crank-throw  0,  M.  The  explosion  pressure  resolves  itself 
into  the  force  F  exerted  along  the  line  of  the  connecting 
rod  A,  M,  and  also  into  a  force  N,  which  tends  to  make 


\ 


Firing  Order 
1-3-5-7-9-2-4*6-8 


Fig.  222. — Diagrams  Showing  Le  Rhone  Motor  Action  and  Firing  Order. 

the  cylinders  rotate  around  point  0  in  the  direction  of 
the  arrow.  An  odd  number  of  cylinders  acting  on  one 
crank-pin  is  desirable  to  secure  equally  spaced  explosions, 
as  the  basic  action  is  the  same  as  the  Gnome  engine. 

The  magneto  is  driven  by  a  gear  having  36  teeth  at- 
tached to  crank-case  which  meshes  with  16-tooth  pinion 
on  armature.  The  magneto  turns  at  2.25  times  crank- 
case  speed.  Two  cams,  one  for  inlet,  one  for  exhaust, 
are  mounted  on  a  carrying  member  and  act  on  nine 
rocker  arms  which  are  capable  of  giving  a  push-and-pull 


504 


Aviation  Engines 


motion  to  the  valve-actuating  rocker-operating  rods.  A 
gear  driven  by  the  crank-case  meshes  with  a  larger  mem- 
ber having  internal  teeth  carried  by  the  cam  carrier. 
Each  cam  has  five  profiles  and  is  mounted  in  staggered 


Top  Dead 
Center 


Bottom  Dead 
Center 


Fig.  223.— Diagram  Showing  Positions  of  Piston  in  Le  Rhone  Rotary 

Cylinder  Motor. 

relation  to  the  other.  These  give  the  nine  fulcrumed 
levers  the  proper  motion  to  open  the  inlet  and  exhaust 
valves  at  the  proper  time.  The  cams  are  driven  at 
4%o  or  %0  of  the  motor  speed.  The  cylinder  dimensions 
and  timing  follows;  the  weight  can  be  approximated  by 
figuring  3  pounds  per  horse-power. 


Renault  Air-Cooled  Vee  Engine 


505 


80  H.  P .105  M/M  bore 4.20"  bore. 

140  M/M  stroke 5.60"  stroke. 

110  H.  P 112  M/M  bore 4.48"  bore. 

170  M/M  stroke 6.80"  stroke. 

Timing— Intake  valve  opening,  lag 18°"^  180>| 

Intake  valve  closing,  lag 35°  35°  I 

Exhaust  valve  opening,  lead 55°  i-110  H.  P.     45°  ^80  H.  P. 

Exhaust  valve  closing,  lag 5°  |  5°  I 

Ignition  time  advance 26°J  26°J 


THE    RENAULT    AIR-COOLED   VEE    ENGINE 

Air-cooled  stationary  engines  are  rarely  used  in  air- 
planes, but  the  Eenault  Freres  of  France  have  for  several 
years  manufactured  a  complete  series  of  such  engines  of 
the  general  design  shown  at  Fig.  225,  ranging  from  a 


Opening  of  Inlet  Valve 

i\ 


Inlet  Valve  Closing 


Igri it/on  Point 
C 


Firing  Order 
1-3-5-7-9-2-4-6-8 


Opening  of  Exhaust 
D 


Exhaust  Voilve  Closing 


Fig.  22*. — Diagrams  Showing  Valve  Timing  of  Le  Rhone  Aviation  Engine. 

v 


506 


Aviation  Engines 


low-powered  one  developed  eight  or  nine  years  ago  and 
rated  at  40  and  50  horse-power,  to  later  eight-cylinder 


Blower  Casing 


-•  flir-coolect 
'    Cylinders 


,-Hot  Air  Pipe 
to  Carburetor 


Casing 


'Supporting  Tubes 


Fig.  225. — Diagrams  Showing  How  Cylinder  Cooling  is  Effected  in 
Renault  Vee  Engines. 

models  rated  at  70  horse-power  and  a  twelve-cylinder,  or 
twin  six,  rated  at  90  horse-power.  The  cylinders  are  of 
cast  iron  and  are  furnished  with  numerous  cooling  ribs 


Renault  Air-Cooled  Vee  Engine 


507 


which  are  cast  integrally.  The  cylinder  heads  are  sepa- 
rate castings  and  are  attached  to  the  cylinder  as  in  early 
motorcycle  engine  practice,  and  serve  to  hold  the  cylinder 
in  place  on  the  aluminum  alloy  crank-case  by  a  cruciform 
yoke  and  four  long  hold-down  bolts  (Fig.  226).  The 


,-Exhaust  Valve  Operating  Rod 


Exhaust  Valve  Eyhaust 

<  Valve 
.-•Spring 


Cylinder  hold 
down  hluts-. 


Cylinder 

Hold  down  Bolts-**.;''' 


Supporting  Tube-'' 
Breather- 


Spark  Plugs—*., 


Inlet  Valve %.- 

Valve  Spring — : 


Crank  Shaft 

Oil  Pump  Drive  Rod 

Oil  Strainer JL 

Oil  Pump 


Fig.  226. — End  Sectional  View  of  Renault  Air-Cooled  Aviation  Engine. 

pistons  are  of  cast  steel  and  utilize  piston  rings  of  cast 
iron.  The  valves  are  situated  on  the  inner  side  of  the 
cylinder  head,  the  arrangement  being  unconventional  in 
that  the  exhaust  valves  are  placed  above  the  inlet.  The 
inlet  valves  seat  in  an  extension  of  the  combustion  head 
and  are  actuated  by  direct  push  rod  and  cam  in  the  usual 
manner  while  an  overhead  gear  in  which  rockers  are  oper- 


508  Aviation  Engines 

ated  by  push  rods  is  needed  to  actuate  the  exhaust  valves. 
The  valve  action  is  clearly  shown  in  Figs.  226  and  227. 
The  air  stream  "by  which  the  cylinders  are  cooled  is  pro- 
duced by  a  centrifugal  or  blower  type  fan  of  relatively 
large  diameter  which  is  mounted  on  the  end  of  a  crank- 
shaft and  the  air  blast  is  delivered  from  this  blower  into 
an  enclosed  space  between  the  cylinder  from  which  it 
escapes  only  after  passing  over  the  cooling  fins.  In 
spite  of  the  fact  that  considerable  prejudice  exists  against 
air-cooling  fixed  cylinder  engines,  the  Eenault  has  given 
very  good  service  in  both  England  and  France. 

As  will  be  seen  by  the  sectional  view  at  Fig.  227,  the 
steel  crank-shaft  is  carried  in  a  combination  of  plain 
bearings  inside  the  crank-case  and  by  ball  bearings  at  the 
ends.  Owing  to  air  cooling,  special  precautions  are  taken 
with  the  lubrication  system,  though  the  lubrication  is  not 
forced  or  under  high  pressure.  An  oil  pump  of  the  gear- 
.wheel  type  delivers  oil  from  the  sump  at  the  bottom  of  the 
crank-case  to  a  chamber  above,  from  which  the  oil  flows 
by  gravity  along  suitable  channels  to  the  various  main 
bearings.  It  flows  from  the  bearings  into  hollow  rings 
fastened  to  the  crank-webs,  and  the  oil  thrown  from  the 
whirling  connecting  rod  big  ends  bathes  the  internal 
parts  in  an  oil  mist.  In  the  eight-cylinder  designs  igni- 
tion is  effected  by  a  magneto  giving  four  sparks  per  revo- 
lution and  is  accordingly  driven  at  engine  speed.  In  the 
twelve-cylinder  machine  two  magnetos  of  the  ordinary 
revolving  armature  or  two-spark  type,  each  supplying 
six  cylinders,  are  fitted  as  outlined  at  Fig.  228.  The 
carburetor  is  a  float  feed  form.  Warm  air  is  supplied 
for  Winter  and  damp  weather  by  air  pipes  surrounding 
the  exhaust  pipes.  The  normal  speed  of  the  Renault 
engine  is  1,800  R.  P.  M.,  but  as  the  propeller  is  mounted 
upon  an  extension  of  the  cam-shaft  the  normal  propeller 
speed  is  but  half  that  of  the  engine,  which  makes  it  pos- 
sible to  use  a  propeller  of  large  diameter  and  high  effi- 
ciency. Owing  to  the  air  cooling,  but  low  compression 
may  be  used,  this  being  about  60  pounds  per  square  inch, 


^09 


510 


Aviation  Engines 


which,  of  course,  lowers  the  mean  effective  pressure  and 
makes  the  engine  less  efficient  than  water-cooled  forms 
where  it  is  possible  to  use  compression  "pressure  of  100 


/  Magnetos 
•      Magneto 


/Distributor 


Engine    ^    » 
Supporting1 
Tube 


Crank  Case  Lower 
half  and  Oil  Sump 


Oil  Filler  and 
Breather  Pipe 


Fig.  228. — End  View  of  Renault  Twelve-Cylinder  Engine  Crank-Case, 
Showing  Magneto  Mounting. 


I 

a 


511 


512  Aviation  Engines 

or  more  pounds  per  square  inch.  The  70  horse-power 
engine  has  cylinders  with  a  bore  of  3.78  inches  and  a 
stroke  of  5.52  inches.  Its  weight  is  given  as  396  pounds, 
when  in  running  order,  which  figures  5.7  pounds  per 
horse-power.  The  same  cylinder  size  is  used  on  the 
twelve-cylinder  100  horse-power  and  the  stroke  is  the 
same.  This  engine  in  running  order  weighs  638  pounds, 
which  figures  approximately  6.4  pounds  per  B.  H.  P. 

SIMPLEX    MODEL.   "A"    HISPANO-STJIZA 

The  Model  A  is  of  the  water-cooled  four-cycle  Vee 
type,  with  eight  cylinders,  4.7245  inch  bore  by  5.1182  inch 
stroke,  piston  displacement  718  cubic  inches.  At  sea-level 
it  develops  150  horse-power  at  1,450  E.  P.  M.  It  can 
be  run  successfully  at  much  higher  speeds,  depending 
on  propeller  design  and  gearing,  developing  proportion- 
ately increased  power.  The  weight,  including  carburetor, 
two  magnetos,  propeller  hub,  starting  magneto  and  crank, 
but  without  radiator,  water  or  oil  or  exhaust  pipes,  is 
445  pounds.  Average  fuel  consumption  is  .5  pound  per 
horse-power  hour  and  the  oil  consumption  at  1,450  E.  P. 
M.  is  three  quarts  per  hour.  The  external  appearance  is 
shown  at  Fig.  230. 

Four  cylinders  are  contained  in  each  block,  which  is 
of  built-up  construction;  the  water  jackets  and  valve 
ports  are  cast  aluminum  and  the  individual  cylinders 
heat-treated  steel  forgings  threaded  into  the  bored  holes 
of  the  aluminum  castings.  Each  block  after  assembly  is 
given  a  number  of  protective  coats  of  enamel,  both  inside 
and  out,  baked  on.  Coats  on  the  inside  are  applied 
under  pressure.  The  pistons  are  aluminum  castings, 
ribbed.  Connecting  rods  are  tubular,  of  the  forked  type. 
One  rod  bears  directly  on  the  crank-pin;  the  other  rod 
has  a  bearing  on  the  outside  of  the  one  first  mentioned. 

The  crank-shaft  is  of  the  five-bearing  type,  very  short, 
stiff  in  design,  bored  for  lightness  and  for  the  oiling 
system.  -  The  crank-shaft  extension  is  tapered  for  the 


His pano- Suiza  Engine  513 

French  standard  propeller  hub,  which  is  keyed  and 
locked  to  the  shaft.  This  makes  possible  instant  change 
of  propellers.  The  case  is  in  two  halves  divided  on  the 
center  line  of  the  crank-shaft,  the  bearings  being  fitted 
between  the  upper  and  lower  sections.  The  lower  half 
is  deep,  providing  a  large  oil  reservoir  and  stiffening 
the  engine.  The  upper  half  is  simple  and  provides  mag- 
neto supports  on  extension  ledges  of  the  two  main  faces. 
The  valves  are  of  large  diameter  with  hollow  stems, 


Fig.  230. — The  Simplex  Model  A  Hispano-Suiza  Aviation  Engine,  a  Very 

Successful  Form. 

working  in  cast  iron  bushings.  They  are  directly  operated 
by  a  single  hollow  cam-shaft  located  over  the  valves.  The 
cam-shafts  are  driven  from  the  crank-shaft  by  vertical 
shafts  and  bevel  gears.  The  cam-shafts,  cams  and  heads 
of  the  valve  stems  are  all  enclosed  in  oil-tight  removable 
housings  of  cast  aluminum. 

Oiling  is  by  a  positive  pressure  system.  The  oil  is 
taken  through  a  filter  and  steel  tubes  cast  in  the  case 
to  main  bearings,  through  crank-shaft  to  crank-pins. 
The  fourth  main  bearing  is  also  provided  with  an  oil 
lead  from  the  system  and  through  tubes  running  up  the 
end  of  each  cylinder  block,  oil  is  provided  for  the  cam- 


514  Aviation  Engines 

shafts,  cams  and  bearings.  The  surplus  oil  escapes 
through  the  end  of  the  cam-shaft  where  the  driving  gears 
are  mounted,  and  with  the  oil  that  has  gathered  in  the 
top  casing,  descends  through  the  drive  shaft  and  gears 
to  the  sump. 

Ignition  is  by  two  eight-cylinder  magnetos  firing  two 
spark-plugs  per  cylinder.  The  magnetos  are  driven 
from  each  of  the  two  vertical  shafts  by  small  bevel 
pinions  meshing  in  bevel  gears.  The  carburetor  is 
mounted  between  the  two  cylinder  blocks  and  feeds  the 
two  blocks  through  aluminum  manifolds  which  are  partly 
water-jacketed.  The  engine  can  be  equipped  with  a 
geared  hand  crank-starting  device. 

STURTEVANT    MODEL   5A    140   HORSE-POWER   ENGINE 

These  motors  are  of  the  eight-cylinder  "V"  type,  four- 
stroke  cycle,  water-cooled,  having  a  bore  of  4  inches  and 
a  stroke  of  5%  inches,  equivalent  to  102  mm.  x  140  mm. 
The  normal  operating  speed  of  the  crank-shaft  is  2,000 
E.  P.  M.  The  propeller  shaft  is  driven  through  reducing 
gears  which  can  be  furnished  in  different  gear  ratios. 
The  standard  ratio  is  5.3,  allowing  a  propeller  speed  of 
1,200  E.  P.  M. 

The  construction  of  the  motor  is  such  as  to  permit 
of  the  application  of  a  direct  drive.  The  change  from  the 
direct  drive  to  gear  drive,  or  vice  versa,  can  be  accom- 
plished in  approximately  one  hour. 

The  cylinders  are  cast  in  pairs  from  an  aluminum 
alloy  and  are  provided  with  steel  sleeves,  carefully  fitted 
into  each  cylinder.  A  perfect  contact  is  secured  between 
cylinder  and  sleeve;  at  the  same  time  a  sleeve  can  be 
replaced  without  injury  to  the  cylinder  proper.  No  dif- 
ficulties due  to  expansion  occur  on  account  of  the  rapid 
transmission  of  heat  and  the  fact  that  the  sleeve  is  al- 
ways at  higher  temperature  than  the  cylinder.  A  moulded 
copper  asbestos  gasket  is  placed  between  the  cylinder 
and  the  head,  permitting  the  cooling  water  to  circulate 


Sturtevant  Model  5 A  Engine  515 

freely  and  at  the  same  time  insuring  a  tight  joint.  The 
cylinder  heads  are  cast  in  pairs  from  an  aluminum  alloy 
and  contain  ample  water  passages  for  circulation  of 
cooling  water  over  the  entire  head.  Trouble  due  to  hot 
valves  is  thereby  eliminated,  a  most  important  consid- 
eration in  the  operation  of  an  aeroplane  motor.  The 
water  jacket  of  the  head  corresponds  to  the  water  jacket 
of  the  cylinders  and  large  openings  in  both  allow  the 
unobstructed  circulation  of  the  cooling  water.  The  cylin- 
der heads  and  cylinders  are  both  held  to  the  base  by  six 
long  bolts.  The  valves  are  located  in  the  cylinder  heads 
and  are  mechanically  operated.  The  valves  and  valve 
springs  are  especially  accessible  and  of  such  size  as  to 
permit  high  volumetric  efficiency.  The  valves  are  con- 
structed of  hardened  tungsten  steel,  the  heads  and  stems 
being  made  from  one  piece.  The  valve  rocker  arms 
located  on  the  top  of  the  cylinder  are  provided  with 
adjusting  screws.  A  check  nut  enables  the  adjusting 
screw  to  be  securely  locked  in  position,  once  the  correct 
clearance  has  been  determined.  The  rocker  arm  bearings 
are  adequately  lubricated  by  a  compression  grease  cup: 
Cam-rollers  are  interposed  between  the  cams  and  the 
push  rods  in  order  to  reduce  the  side  thrust  on  the  push 
rods. 

A  system  of  double  springs  is  employed  which  greatly 
reduces  the  stress  on  each  spring  and  insures  utmost 
reliability.  A  spring  of  extremely  large  diameter  returns 
the  valve;  a  second  spring  located  at  the  cylinder  base 
handles  the  push  rod  linkage.  These  springs,  which 
operate  under  low  stress,  are  made  from  the  best  of  steel 
and  are  given  a  special  double  heat  treatment.  The 
pistons  are  made  from  a  special  aluminum  alloy;  are 
deeply  ribbed  in  the  head  for  cooling  and  strength  and 
provided  with  two  piston  rings.  These  pistons  are  ex- 
ceedingly light  weight  in  order  to  minimize  vibration  and 
prevent  wear  on  the  bearings.  The  piston  pin  is  made  of 
chrome  nickel  steel,  bored  hollow  and  hardened.  It  is 
allowed  to  turn,  both  in  piston  and  connecting  rod.  The 


516  Aviation  Engines 

piston  rings  are  of  special  design,  developed  after  years 
of  experimenting  in  aeronautical  engines. 

The  connecting  rods  are  of  "H"  section,  machined 
all  over  from  forgings  of  a  special  air-hardening  chrome 
nickel  steel  which,  after  being  heat  treated  has- a  tensile 
strength  of  280,000  pounds  per  square  inch.  They  are 
consequently  very  strong  and  yet  unusually  light,  and 
being  machined  all  over  are  of  absolutely  uniform  section, 
which  gives  as  nearly  perfect  balance  as  can  be  obtained. 
The  big  ends  are  lined  with  white  metal  and  the  small 
ends  are  bushed  with  phosphor  bronze.  The  connecting 
rods  are  all  alike  and  take  their  bearings  side  by  side  on 
the  crank-pin,  the  cylinders  being  offset  to  permit  of 
this  arrangement.  The  crank-shaft  is  machined  from 
the  highest  grade  chrome  nickel  steel,  heat  treated  in 
order  to  obtain  the  best  properties  of  this  material. 
It  is  2%  inches  in  diameter  (57  mm.)  and  bored  hollow 
throughout,  insuring  maximum  strength  with  minimum 
weight.  It  is  carried  in  three  large,  bronze-backed  white 
metal  bearings.  A  new  method  of  producing  these  bear- 
•ings  insures  a  perfect  bond  between  the  two  metals  and 
eliminates  breakage. 

The  base  is  cast  from  an  aluminum  alloy.  Great 
strength  and  rigidity  is  combined  with  light  weight.  The 
sides  extend  considerably  below  the  center  line  of  the 
crank-shaft,  providing  an  extremely  deep  section.  At 
all  highly  stressed  points,  deep  ribs  are  provided  to  dis- 
tribute the  load  evenly  and  eliminate  bending.  The  lower 
half  of  the  base  is  of  cast  aluminum  alloy  of  extreme 
lightness.  This  collects  the  lubricating  oil  and  acts  as 
a  small  reservoir  for  same.  An  oil-filtering  screen  of 
large  area  covers  the  entire  surface  of  the  sump.  The 
propeller  shaft  is  carried  on  two  large  annular  ball  bear- 
ings driven  from  the  crank- shaft  by  hardened  chrome 
nickel  steel  spur  gears.  These  gears  are  contained  within 
an  oil-tight  casing  integral  with  the  base  on  the  oppo- 
site end  from  the  timing  gears.  A  ball -thrust  bearing 
is  provided  on  the  propeller  shaft  to  take  the  thrust  of 


Sturtevant  Model  5 A  Engine  517 

a  propeller  or  tractor,  as  the  case  may  be.  In  case  of  the 
direct  drive  a  stub  shaft  is  fastened  direct  to  the  crank- 
shaft and  is  fitted  with  a  double  thrust  bearing. 

The  cam-shaft  is  contained  within  the  upper  half  of 
the  base  between  the  two  groups  of  cylinders,  and  is 
supported  in  six  bronze  bearings.  It  is  bored  hollow 
throughout  and  the  cams  are  formed  integral  with  the 
shaft  and  ground  to  the  proper  shape  and  finish.  An 
important  development  in  the  shape  of  cams  has  resulted 
in  a  maintained  increase  of  power  at  high  speeds.  The 
gears  operating  the  cam-shaft,  magneto,  oil  and  water 
pumps  are  contained  within  an  oil-tight  casing  and  oper- 
ate in  a  bath  of  oil. 

Lubrication  is  of  the  complete  forced  circulating  sys- 
tem, the  oil  being  supplied  to  every  bearing  under  high 
pressure  by  a  rotary  pump  of  large  capacity.  This  is 
operated  by  gears  from  the  crank-shaft.  The  oil  passages 
from  the  pump  to  the  main  bearings  are  cast  integral 
with  the  base,  the  hollow  crank-shaft  forming  a  passage 
through  the  connecting  rod  bearings  and  the  hollow  cam- 
shaft distributing  the  oil  to  the  cam-shaft  bearings.  The 
entire  surface  of  the  lower  half  of  the  base  is  covered 
with  a  fine  mesh  screen  through  which  the  oil  passes 
before  reaching  the  pump.  Approximately  one  gallon  of 
oil  is  contained  within  the  base  and  this  is  continually 
circulated  through  an  external  tank  by  a  secondary  pump 
operated  by  an  eccentric  on  the  cam-shaft.  This  also 
draws  fresh  oil  from  the  external  tank  which  can  be  made 
of  any  desired  capacity. 

SPECIFICATIONS MODEL   5A  TYPE   8 

Horse-power  rating,  140  at  2,000  E.  P.  M. 

Bore,  4  inches  =  102  mm. 

Stroke,  5^  inches  =  140  mm. 

Number  of  cylinders,  8. 

Arrangement  of  cylinders,  "V." 

Cooling,   water.     Circulation  by  centrifugal  pump. 


518  Aviation  Engines 

Cycle,  four  stroke. 

Ignition  (double),  2  Bosch  or  Splitdorf  magnetos. 

Carburetor,  Zenith   duplex.     Water   jacket   manifold. 

Oiling  system,  complete  forced.     Circulating  gear  pump. 

Normal  crank-shaft  speed,  2,000  E.  P.  M. 

Propeller   shaft,    %    crank-shaft    speed   at   normal,    1,200 

E.  P.  M. 

Stated  power  at  30"  barometer,  140  B.  H.  P. 
Stated   weight   with   all   accessories   but   without    water, 

gasoline  or  oil,  514  pounds  =  234  kilos. 
Weight  per  B.  H.  P.,  3.7  pounds  =  1.68  kilos. 
Stated  weight  with  all  accessories  with  water,  550  pounds 

-250  kilos. 
Weight   per    B.    H.    P.    with    water,    3.95    pounds  =  1.79 

kilos. 

THE    CURTISS   AVIATION    MOTORS 

The  Curtiss  OX  motor  has  eight  cylinders,  4-inch 
bore,  5-inch  stroke,  delivers  90  horse-power  at  1,400  turns, 
and  the  weight  turns  out  at  4.17  pounds  per  horse-power. 
This  motor  has  cast  iron  cylinders  with  monel  metal 
jackets,  overhead  inclined  valves  operated  by  means  of 
two  rocker  arms,  push-and-pull  rods  from  the  central 
cam-shaft  located  in  the  crank-case.  The  cam  and  push 
rod  design  is  extremely  ingenious  and  the  whole  valve 
construction  turns  out  very  light.  This  motor  is  an 
evolution  from  the  early  Curtiss  type  motor  which  was 
used  by  Glenn  Curtiss  when  he  won  the  Gordon  Bennett 
Cup  at  Eheims.  A  slightly  larger  edition  of  this  type 
motor  is  the  OXX  5,  as  shown  at  Figs.  231  and  232, 
which  has  cylinders  4^  inches  by  5  inches,  delivers  100 
horse-power  at  1,400  turns  and  has  the  same  fuel  and 
oil  consumption  as  the  OX  type  motor,  namely,  .60  pound 
of  fuel  per  brake  horse-power  hour  and  .03  pound  of 
lubricating  oil  per  brake  horse-power  hour. 

The  Curtiss  Company  have  developed  in  the  last 
two  years  a  larger-sized  motor  now  known  as  •  the  V-2, 
which  was  originally  rated  at  160  horse-power  and  which 


Curtis s  Aviation  Motors 


519 


has  since  been  refined  and  improved  so  that  the  motor 
gives  220  horse-power  at  1,400  turns,  with  a  fuel  con- 
sumption of  5%oo  of  a  pound  per  brake  horse-power  hour 
and  an  oil  consumption  of  .02  of  a  pound  per  brake 
horse-power  hour.  This  larger  motor  has  a  weight  of  3.45 
pounds  per  horse-power  and  is  now  said  to  be  giving 


ive    Action 


Water-"" 
Jacketed      * 
Intake  Pipe  ^ 

Y 


Oil  Gauge 


arburetor 


Fig.  231.— The  Curtiss  OXX5  Aviation  Engine  is  an  Eight-Cylinder  Type 
Largely  Used  on  Training  Machines. 

very  satisfactory  service.  The  V-2  motor  has  drawn 
steel  cylinders,  with  a  bore  of  5  inches  and  a  stroke  of 
7  inches,  with  a  steel  water  jacket  top  and  a  monel  metal 
cylindrical  jacket,  both  of  which  are  brazed  on  to  the 
cylinder  barrel  itself.  Both  these  motors  use  side  by 
side  connecting  rods  and  fully  forced  lubrication.  The 
cam-shafts  act  as  a  gallery  from  which  the  oil  is  dis- 
tributed to  the  cam-shaft  bearings,  the  main  crank- shaft 


520 


Aviation  Engines 


bearings,  and  the  gearing.  Here  again  we  find  extremely 
short  rods,  which,  as  before  mentioned,  enables  the  height 
and  the  consequent  weight  of  construction  to  be  very 
much  reduced.  For  ordinary  flying  at  altitudes  of  5,000 


Propeller 
Hub 


A 

Viewed  "From 
Top 


Removable  Sump  Screen 


Carburetor 


Viewed  "from 
Bottom  * 


Water  ft  pe 


Fig.  232.— Top  and  Bottom  Views  of  the  Curtiss  OXX5  100  Horse-Power 

Aviation  Engine. 

to  6,000  feet,  the  motors  are  sent  out  with  an  aluminum 
liner,  bolted  between  the  cylinder  and  the  crank-case  in 
order  to  give  a  compression  ratio  which  does  not  result 
in  pre-ignition  at  a  low  altitude.  For  high  flying,  how- 
ever, these  aluminum  liners  are  taken  out  and,  the  com- 


Thomas  Morse  Engine  521 

pression  volume  is  decreased  to  about  18.6  per  cent,  of 
the  total  volume. 

The  Curtiss  Aeroplane  Company  announces  that  it  has 
recently  built,  and  is  offering,  a  twelve-cylinder  5"  x  7" 
motor,  which  was  designed  for  aeronautical  uses  primar- 
ily. This  engine  is  rated  at  250  horse-power,  but  it  is 
claimed  to  develop  300  at  1,400  E.  P.  M.  Weights— Motor, 
1,125  pounds;  radiator,  120  pounds;  cooling  water,  100 
pounds;  propeller,  95  pounds. 

Gasoline  Consumption  per  Horse-power  Hour,  %o 
pounds. 

Oil  Consumption  per  Hour  at  Maximum  Speed — 2 
pints. 

Installation  Dimensions — Overall  length,  84%  inches; 
overall  width,  34%  inches;  overall  depth,  40  inches; 
width  at  bed,  30%  inches;  height  from  bed,  21%  inches; 
depth  from  bed,  18%  inches. 

THOMAS-MORSE    MODEL    88    ENGINE 

The  Thomas-Morse  Aircraft  Corporation  of  Ithaca, 
N.  Y.,  has  produced  a  new  engine,  Model  88,  bearing  a 
close  resemblance  to  the  earlier  model.  The  main  features 
of  that  model  have  been  retained;  in  fact,  many  parts 
are  interchangeable  in  the  two  engines.  Supported  by 
the  great  development  in  the  wide  use  of  aluminum,  the 
Thomas  engineers  have  adopted  this  material  for  cylinder 
construction,  which  adoption  forms  the  main  departure 
from  previous  accepted  design. 

The  marked  tendency  to-day  toward  a  higher  speed 
of  rotation  has  been  conclusively  justified,  in  the  opinion 
of  the  Thomas  engineers,  by  the  continued  reliable  per- 
formance of  engines  with  crank-shafts  operating  at  speeds 
near  2,000  revolutions  per  minute,  driving  the  propeller 
through  suitable  gearing  at  the  most  efficient  speed. 
High  speed  demands  that  the  closest  attention  be  paid 
to  the  design  of  reciprocating  and  rotating  parts  and 
their  adjacent  units.  Steel  of  the  highest  obtainable 


522  Aviation  Engines 

tensile  strength  must  be  used  for  connecting  rods  and 
piston  pins,  that  they  may  be  light  and  yet  retain  a 
sufficient  factor  of  safety.  Piston  design  is  likewise 
subjected  to  the  same  strict  scrutiny.  At  the  present 
day,  aluminum  alloy  pistons  operate  so  satisfactorily 
that  they  may  be  said  to  have  come  to  stay. 

The  statement  often  made  in  the  past,  that  the  gear- 
ing down  of  an  engine  costs  more  in  the  weight  of  re- 
duction gears  and  propeller  shaft  than  is  warranted  by 
the  increase  in  horse-power,  is  seldom  heard  to-day. 

The  mean  effective  pressure  remaining  the  same,  the 
brake  horse-power  of  any  engine  increases  as  the  speed. 
That  is,  an  engine  delivering  100  brake  horse-power  at 
1,500  revolutions  per  minute  will  show  133  brake  horse- 
power at  2,000  revolutions  per  minute,  an  increase  of  33 
brake  horse-power.  To  utilize  this  increase  in  horse- 
power, a  matter  of  some  fifteen  pounds  must  be  spent 
in  gearing  and  another  fifteen  perhaps  on  larger  valves, 
bearings,  etc.  Two  per  cent,  may  be  assumed  lost  in 
the  gears.  In  other  words,  the  increase  in  horse-power 
due  to  increasing  the  speed  has  been  attained  at  the 
expense  of  about  one  pound  per  brake  horse-power. 

The  advantages  of  the  eight-cylinder  engine  over  the 
six  and  twelve,  briefly  stated,  are :  lower  weight  per  horse- 
power, shorter  length,  simpler  and  stiffer  crank-shaft, 
cam-shaft  and  crank-case,  and  simpler  and  more  direct 
manifold  arrangement.  As  to  torque,  the  eight  is  supe- 
rior to  the  six,  and  yet  in  practice  not  enough  inferior 
to  the  twelve  to  warrant  the  addition  of  four  more 
cylinders.  It  must,  however,  be  recognized  that  the 
eight  is  subject  to  the  action  of  inherent  unbalanced 
inertia  couples,  which  set  up  horizontal  vibrations,  im- 
possible of  total  elimination.  These  vibrations  are  func- 
tions of  the  reciprocating  weights,  which,  as  already 
mentioned,  are  cut  down  to  the  minimum.  Vibrations 
due  to  the  elasticity  of  crank-case,  crank-shaft,  etc.,  -can 
be  and  are  reduced  in  the  Thomas  engine  to  minor 
quantities  by  ample  webbing  of  the  crank-case  and  judi- 


Thomas -Morse  Engine  523 

cious  use  of  metal  elsewhere.  All  things  considered, 
there  is  actually  so  little  difference  to  be  discerned  be- 
tween the  balance  of  a  properly  designed  eight-cylinder 
engine  and  that  of  a  six  or  twelve  as  to  make  a  dis- 
cussion of  the  pros  and  cons  more  one  of  theory  than 
of  practice. 

The  main  criticisms  of  the  L  head  cylinder  engine  are 
that  it  is  less  efficient  and  heavier.  This  is  granted,  as  it 
relates  to  cylinders  alone.  More  thorough  investigation, 
however,  based  on  the  main  desideratum,  weight-power 
ratio,  leads  us  to  other  conclusions,  particularly  with 
reference  to  high  speed  engines.  The  valve  gear  must 
not  be  forgotten.  A  cylinder  cannot  be  taken  completely 
away  from  its  component  parts  and  judged,  as  to  its 
weight  value,  by  itself  alone.  A  part  away  from  the  whole 
becomes  an  item  unimportant  in  comparison  with  the 
whole.  The  valve  gear  of  a  high  speed  engine  is  a  too 
often  overlooked  feature.  The  stamp  of  approval  has 
been  made  by  high  speed  automobile  practice  upon  the 
overhead  cam-shaft  drive,  with  valves  in  the  cylinder 
head  operated  direct  from  the  cam-shaft  or  by  means  of 
valve  lifters  or  short  rockers. 

The  overhead  cam-shaft  mechanism  applied  to  an 
eight-cylinder  engine  calls  for  two  separate  cam-shafts 
carried  above  and  supported  by  the  cylinders  in  an  oil- 
tight  housing,  and  driven  by  a  series  of  spur  gears  or 
bevels  from  the  crank-shaft.  It  is  patent  that  this  valve 
gearing  is  heavy  and  complicated  in  comparison  with 
the  simple  moving  valve  units  of  the  L  head  engine, 
which  are  operated  from  one  single  cam-shaft,  housed 
rigidly  in  the  crank-case.  The  inherently  lower  volu- 
metric efficiency  of  the  L  head  engine  is  largely  overcome 
by  the  use  of  a  properly  designed  head,  large  valves  and 
ample  gas  passages.  Again,  the  customary  use  of  a  dual 
ignition  system  gives  to  the  L  head  a  relatively  better 
opportunity  for  the  advantageous  placing  of  spark-plugs, 
in  order  that  better  flame  propagation  and  complete 
combustion  may  be  secured. 


524 


Aviation  Engines 


The  Thomas  Model  88  engine  is  4%-inch  bore  and 
5%-inch  stroke.  The  cylinders  and  cylinder  heads  are 
of  aluminum,  and  as  steel  liners  are  used  in  the  cylinders 


Fig.  233. — End  View  of  Thomas-Morse  150  Horse-Power  Aluminum  Cylinder 
Aviation  Motor  Having  Detachable  Cylinder  Heads. 

the  pistons  are  also  made  of  aluminum.  This  engine  is 
actually  lighter  than  the  earlier  model  of  less  power. 
It  weighs  but  525  pounds,  with  self-starter.  The  general 


Sixteen-V 'alve  Duesenberg  Engine 


525 


features  of  design  can  be  readily  ascertained  by  study 
of  the  illustrations :  Fig.  233,  which  shows  an  end  view ; 
Fig.  234,  which  is  a  side  view,  and  Fig.  235,  which  out- 


Fig.  234. — Side  View  of  Thomas-Morse  High  Speed  150  Horse-Power 
Aviation  Motor  with  Geared  Down  Propeller  Drive. 

lines   the   reduction   gear-case    and   the   propeller    shaft 
supporting  bearings. 


SIXTEEN-VALVE    DUESENBERG    ENGINE 

This  engine  is  a  four-cylinder,  4%"x7",  125  horse- 
power at  2,100  E.  P.  M.  of  the  crank-shaft  and  1,210 
E.  P.  M.  of  the  propeller.  Motors  are  sold  on  above 
rating;  actual  power  tests  prove  this  motor  capable  of 
developing  140  horse-power  at  2,100  E.  P.  M.  of  the 
motor.  The  exact  weight  with  magneto,  carburetor,  gear 
reduction  and  propeller  hub,  as  illustrated,  509  pounds; 
without  gear  reduction,  436  pounds.  This  motor  has 
been  produced  as  a  power  plant  weighing  3.5  pounds  per 
horse-power,  yet  nothing  has  been  sacrificed  in  rigidity 
and  strength.  At  its  normal  speed  it  develops  1  horse- 


526 


Aviation  Engines 


power  for  every  3.5  cubic  inches  piston  displacement. 
Cylinders  are  semi-steel,  with  aluminum  plates  enclosing 
water  jackets.  Pistons  specially  ribbed  and  made  of 
Magnalite  aluminum  compound.  Piston  rings  are  special 
Duesenberg  design,  being  three-piece  rings.  Valves  are 


Fig.   235. — The   Reduction   Gear-Case    of   Thomas-Morse    150    Horse-Power 
Aviation  Motor,  Showing  Ball  Bearing  and  Propeller  Drive  Shaft  Gear. 

tungsten  steel,  11%6"  inlets  and  2"  exhausts,  two  of  each 
to  each  cylinder.  Arranged  horizontally  in  the  head, 
allowing  very  thorough  water- jacketing.  Inlet  valves  in 
cages.  Exhaust  valves,  seating  directly  in  the  cylinder 
head,  are  removable  through  the  inlet  valve  holes.  Valve 
stems  lubricated  by  splash  in  the  valve  action  covers. 
Valve  rocker  arms  forged  with  cap  screw  and  nut  at 


Siocteen-V alve  Dues enb erg  Engine  527 

upper  end  to  adjust  clearance.  Entirely  enclosed  by 
aluminum  housing,  as  is  entire  valve  mechanism.  Con- 
necting rods  are  tubular,  chrome  nickel  steel,  light  and 
strong.  Crank-shaft  is  one-piece  forging,  hollow  bored, 
2i/2-inch  diameter  at  main  bearings.  Connecting  rod 
bearings,  214-inch  diameter,  3  inches  long.  Front  main 
bearing,  3%  inches  long;  intermediate  main  bearing, 
31/2  inches  long ;  rear  main  bearing,  4  inches  long.  Crank- 
case  of  aluminum,  barrel  type,  oil  pan  on  bottom  remov- 
able. Hand  hole  plates  on  both  sides.  Strongly  webbed. 
The  oiling  system  of  this  sixteen-valve  Duesenberg 
motor  is  one  of  its  vital  features.  An  oil  pump  located 
in  the  base  and  submerged  in  oil  forces  oil  through  cored 
passages  to  the  three  main  bearings,  then  through  tubes 
under  each  connecting  rod  into  which  the  rod  dips.  The 
oil  is  thrown  off  from  these  and  lubricates  every  part  of 
the  motor.  This  constitutes  the  main  oiling  system;  it  is 
supplemented  by  a  splash  system,  there  being  a  trough 
under  each  connecting  rod  into  which  the  rod  slips.  The 
oil  is  returned  to  the  main  supply  sump  by  gravity, 
where  it  is  strained  and  re-used.  Either  system  is  in 
itself  sufficient  to  operate  the  motor.  A  pressure  gauge 
is  mounted  for  observation  on  a  convenient  part  of  the 
system.  A  pressure  of  approximately  25  pounds  is 
maintained  by  the  pressure  system,  which  insures  effi- 
cient lubrication  at  all  speeds  of  the  motor.  The  troughs 
under  the  connecting  rods  are  so  constructed  that  no 
matter  what  the  angle  of  flight  may  be,  oil  is  retained 
in  each  individual  trough  so  that  each  connecting  rod 
can  dip  up  its  supply  of  oil  at  each  revolution. 


AEROMARINE     SIX-CYLINDER     VERTICAL     MOTOR 

These  motors  are  four-stroke  cycle,  six-cylinder  ver- 
tical type,  with  cylinder  4«>i«//  bore  by  5%"  stroke.  The 
general  appearance  of  this  motor  is  shown  in  illustra- 
tion at  Fig.  236.  This  engine  is  rated  at  85-90  horse- 
power. All  reciprocating  and  revolving  parts  of  this 


-528  Aviation  Engines 

motor  are  made  of  the  highest  grades  of  steel  obtainable 
as  are  the  studs,  nuts  and  bolts.  The  upper  and  lower 
parts  of  crank-case  are  made  of  composition  aluminum 
casting.  Lower  crank-case  is  made  of  high  grade  alu- 
minum composition  casting  and  is  bolted  directly  to  the 
upper  half.  The  oil  reservoir  in  this  lower  half  casting 
provides  sufficient  oil  capacity  for  five  hours'  continuous 
running  at  full  power.  Increased  capacity  can  be  pro- 


e-Water  Pm'e 

•^tfuraijyfLiJB&HiBiyftLi 

Magneto 


Water  / 
Pum.p 


O'rt  Pump 


Fig.  236. — The  Six-Cylinder  Aeromarine  Engine. 

vided  if  needed  to  meet  greater  endurance  requirements. 
Oil  is  forced  under  pressure  to  all  bearings  by  means  of 
high-pressured  duplex-geared  pumps.  One  side  of  this 
pump  delivers  oil  under  pressure  to  all  the  bearings, 
while  the  other  side  draws  the  oil  from  the  splash  case 
and  delivers  it  to  the  main  sump.  The  oil  reservoir  is 
entirely  separate  from  the  crank-case  chamber.  Under 
no  circumstances  will  oil  flood  the  cylinder,  and  the  oiling 
system  is  not  affected  in  any  way  by  any  angle  of  flight 
or  position  of  motor.  An  oil  pressure  gauge  is  placed 
on  instrument  board  of  machine,  which  gives  at  all  times 


Aeromarine  Aviation  Engine  529 

the  pressure  in  oil  system,  and  a  sight  glass  at  lower 
half  of  case  indicates  the  amount  of  oil  contained.  The 
oil  pump  is  external  on  magneto  end  of  motor,  and  is 
very  accessible.  An  external  oil  strainer  is  provided, 
which  is  removable  in  a  few  minutes'  time  without  the 
loss  of  any  oil.  All  oil  from  reservoir  to  the  motor  passes 
through  this  strainer.  Pressure  gauge  feed  is  also  at- 
tached and  can  be  piped  to  any  part  of  machine  desired. 

The  cylinders  are  made  of  high-grade  castings  and 
are  machined  and  ground  accurately  to  size.  Cylinders 
are  bolted  to  crank-case  with  chrome  nickel  steel  studs 
and  nuts  which  securely  lock  cylinder  to  upper  half  of 
crank-case.  The  main  retaining  cylinder  studs  go 
through  crank-case  and  support  crank-shaft  bearings  so 
that  crank-shaft  and  cylinders  are  tied  together  as  one 
unit.  Water  jackets  are  of  copper,  %e"  thick,  electrically 
deposited.  This  makes  a  non-corrosive  metal.  Cooling 
is  furnished  by  a  centrifugal  pump,  which  delivers  25 
gallons  per  minute  1,400  E.  P.  M.  Pistons  are  made 
cast  iron,  accurately  machined  and  ground  to  exact  di- 
mensions, which  are  carefully  balanced.  Piston  rings  are 
semi- steel  rings  of  Aeromarine  special  design. 

Connecting  rods  are  of  chrome  nickel  steel,  H-section. 
Crank-shaft  is  made  of  chrome  nickel  steel,  machined  all 
over,  and  cut  from  solid  billet,  and  is  accurately  bal- 
anced through  the  medium  of  balance  weights  being 
forged  integral  with  crank.  It  is  drilled  for  lightness  and 
plugged  for  force  feed  lubrication.  There  are  seven 
main  bearings  to  crank-shaft.  All  bearings  are  of  high- 
grade  babbitt,  die  cast,  and  are  interchangeable  and  easily 
replaced.  The  main  bearings  of  the  crank-shaft  are 
provided  with  a  single  groove  to  take  oil  under  pressure 
from  pressure  tube  which  is  cast  integral  with  case. 
Connecting  rod  bearings  are  of  the  same  type.  The 
gudgeon  pin  is  hardened,  ground  and  secured  in  con- 
necting rod,  and  is  allowed  to  work  in  piston.  Cam-shaft 
is  of  steel,  with  cams  forged  integral,  drilled  for  light- 
ness and  forced-feed  lubrication,  and  is  case-hardened. 


530 


Aviation  Engines 


Fig.  237. — The  Wisconsin  Aviation  Engine,  at  Top,  as  Viewed  from 
Carburetor  Side.     Below,  the  Exhaust  Side. 


Wisconsin  Aviation  Engine 


531 


The  bearings  of  cam-shaft  are  of  bronze.  Magneto,  two 
high-tension  Bosch  D.  U.  6.  The  intake  manifold  for 
carburetors  are  aluminum  castings  and  are  so  designed 
that  each  carburetor  feeds  three  cylinders,  thereby  insur- 
ing easy  flow  of  vapor  at  all  speeds.  Weight,  420  pounds. 

WISCONSIN   AVIATION   ENGINES 

The  new  six-cylinder  Wisconsin  aviation  engines,  one 
of  which  is  shown  at  Fig.  237,  are  of  the  vertical  type, 


Fig.  238. — Dimensioned  End  Elevation  of  Wisconsin  Six  Motor. 

with  cylinders  in  pairs  and  valves  in  the  head.  Dimen- 
sioned drawings  of  the  six-cylinder  vertical  type  are 
given  at  Figs.  238  and  239.  The  cylinders  are  made  of 
aluminum  alloy  castings,  are  bored  and  machined  and 
then  fitted  with  hardened  steel  sleeves  about  %e  inch  in 
thickness.  After  these  sleeves  have  been  shrunk  into 
the  cylinders,  they  are  finished  by  grinding  in  place. 
Gray  iron  valve  seats  are  cast  into  the  cylinders.  The 
valve  seats  and  cylinders,  as  well  as  the  valve  ports,  are 


532 


Aviation  Engines 


entirely  surrounded  by  water  jackets.  The  valves  set 
in  the  heads  at  an  angle  of  25°  from  the  vertical,  are 
made  of  tungsten  steel  and  are  provided  with  double 
springs,  the  outer  or  main  spring  and  the  inner  or  aux- 
iliary spring,  which  is  used  as  a  precautionary  measure 
to  prevent  a  valve  falling  into  the  cylinder  in  remote 
case  of  a  main  spring  breaking.  The  cam-shaft  is  made 
of  one  solid  forging,  case-hardened.  It  is  carried  in  an 


Fig.  239. — Dimensioned  Side  Elevation  of  Wisconsin  Six  Motor. 

aluminum  housing  bolted  to  the  top  of  the  cylinders. 
This  housing  is  split  horizontally,  the  upper  half  carrying 
the  chrome  vanadium  steel  rocker  levers.  The  lower  half 
has  an  oil  return  trough  cast  integral,  into  which  the 
excess  oil  overflows  and  then  drains  back  to  the  crank- 
case.  Small  inspection  plates  are  fitted  over  the  cams 
and  inner  ends  of  the  cam  rocker  levers.  The  cam-shaft 
runs  in  bronze  bearings  and  the  drive  is  through  ver- 
tical shaft  and  bevel  gears.  ' 
The  crank-case  is  made  of  aluminum,  the  upper  half 


Wisconsin  Aviation  Engine   •  533 

carrying  the  bearings  for  the  crank-shaft.  The  lower 
half  carries  the  oil  sump  in  which  all  of  the  oil  except 
that  circulating  through  the  system  at  the  time  is  carried. 
The  crank- shaft  is  made  of  chrome  vanadium  steel  of 
an  elastic  limit  of  115,000  pounds.  The  crank-pins  and 
ends  of  the  shaft  are  drilled  for  lightness  and  the  cheeks 
are  also  drilled  for  oil  circulation.  The  crank-shaft  runs 
in  bronze-backed,  Fahrig  metal-lined  bearings,  four  in 
number.  A  double  thrust  bearing  is  also  provided,  so 
that  the  motor  may  be  used  either  in  a  tractor  or  pusher 
type  of  machine.  Outside  of  the  thrust  bearing  an  annu- 
lar ball  bearing  is  used  to  take  the  radial  load  of  the 
propeller.  The  propeller  is  mounted  on  a  taper.  At  the 
opposite  end  of  the  shaft  a  bevel  gear  is  fitted  which 
drives  the  cam-shaft,  through  a  vertical  shaft,  and  also 
drives  the  water  and  oil  pumps  and  magnetos.  All  gears 
are  made  of  chrome  vanadium  steel,  heat-treated. 

The  connecting  rods  are  tubular  and  machined  from 
chrome  vanadium  steel  forgings.  Oil  tubes  are  fitted  to 
the  rods  which  carry  the  oil  up  to  the  wrist-pins  and 
pistons.  The  rods  complete  with  bushings  weigh  5% 
pounds  each.  The  pistons  are  made  of  aluminum  alloy 
and  are  very  light  and  strong,  weighing  only  2  pounds 
2  ounces  each.  Two  leak-proof  rings  are  fitted  to  each 
piston.  The  wrist-pins  are  hollow,  of  hardened  steel, 
and  are  free  to  turn  either  in  the  piston  or  the  rod.  A 
bronze  bushing  is  fitted  in  the  upper  end  of  the  rod,  but 
no  bushing  is  fitted  in  the  pistons,  the  hardened  steel 
wrist-pins  making  an  excellent  bearing  in  the  aluminum 
alloy. 

The  water  circulation  is  by  centrifugal  pump,  which 
is  mounted  at  the  lower  end  of  the  vertical  shaft.  The 
water  is  pumped  through  brass  pipes  to  the  lower  end 
of  the  cylinder  water  jackets  and  leaves  the  upper  end 
of  the  jackets  just  above  the  exhaust  valves.  The  lubri- 
cating system  is  one  of  the  main  features  of  the  engines, 
being  designed  to  wrork  with  the  motor  at  any  angle. 
The  oil  is  carried  in  the  sump,  from  where  it  is  taken 


534 


Aviation  Engines 


by  the  oil  circulating  pump  through  a  strainer  and  forced 
through  a  header,  extending  the  full  length  of  the  crank- 
case,  and  distributed  to  the  main  bearings.  From  the 
main  bearings  it  is  forced  through  the  hollow  crank- 
shaft to  the  connecting  rod  big  ends  and  then  through 


800 


0       ZOO     400     600    800    1000    IZOO     1400    1600     1800    ZOOO  ZZOO    Z400 
Revolutions   per  Minu+e 


Fig.  240. — Power,  Torque  and  Efficiency  Curves  of  Wisconsin  Aviation 

Motor. 


Wisconsin  Aviation  Engine 


535 


tubes  on  the  rods  to  wrist-pins  and  pistons.  Another 
lead  takes  oil  from  the  main  header  to  the  cam-shaft 
bearings.  The  oil  forced  out  of  the  ends  of  the  cam- 
shaft bearings  fills  pockets  under  the  cams  and  in  the 
cam  rocker  levers.  The  excess  flows  back  through  pipes 
and  through  the  train  of  gears  to  the  crank-case.  A 
strainer  is  fitted  at  each  end  of  the  crank-case,  through 
which  the  oil  is  drawn  by  separate  pumps  and  returned 
to  the  sump.  Either  one  of  these  pumps  is  large  enough 


—  Exhaust  Closes 
•     Inlet  Opens 


Firing  Order  I  -  4-2- 6- 3- S 


Fig.  241. — Timing  Diagram,  Wisconsin  Aviation  Engine. 

to  take  care  of  all  of  the  return  oil,  so  that  the  operation 
is  perfect  whether  the  motor  is  inclined  up  or  down.  No 
splash  is  used  in  the  crank-case,  the  system  being  a 
full  force  feed.  An  oil  level  indicator  is  provided,  show- 
ing the  amount  of  oil  in  the  sump  at  all  times.  The  oil 
pressure  in  these  motors  is  carried  at  ten  pounds,  a 
relief  valve  being  fitted  to  hold  the  pressure  constant. 

Ignition  is  by  two  Bosch  magnetos,  each  on  a  separate 
set  of  plugs  fired  simultaneously  on  opposite  sides  of  the 
cylinders.  Should  one  magneto  fail,  the  other  would  still 
run  the  engine  at  only  a  slight  loss  in  power.  The  Zenith 
double  carburetor  is  used,  three  cylinders  being  supplied 
by  each  carburetor.  This  insures  a  higher  volumetric 
efficiency,  which  means  more  power,  as  there  is  no  over- 


536  Aviation  Engines 

lapping  of  inlet  valves  whatever  by  this  arrangement. 
All  parts  of  these  motors  are  very  accessible.  The  water 
and  oil  pumps,  carburetors,  magnetos,  oil  strainer  or 
other  parts  can  be  removed  without  disturbing  other 
parts.  The  lower  crank-case  can  be  removed  for  in- 
spection or  adjustment  of  bearings,  as  the  crank-shaft  and 
bearing  caps  are  carried  by  the  upper  half.  The  motor 
supporting  lugs  are  also  part  of  the  upper  crank-case. 

The  six-cylinder  motor,  without  carburetors  or  mag- 
netos, weighs  547  pounds.  With  carburetor  and  mag- 
netos, the  weight  is  600  pounds.  The  weight  of  cooling 
water  in  the  motor  is  38  pounds.  The  sump  will  carry 
4  gallons  of  oil,  or  about  28  pounds.  A  radiator  can  be 
furnished  suitable  for  the  motor,  weighing  50  pounds. 
This  radiator  will  hold  3  gallons  of  water  or  about  25 
pounds.  The  motor  will  drive  a  two-blade,  8  feet  diame- 
ter by  6.25  feet  pitch  Paragon  propeller  1400  revolutions 
per  minute,  developing  148  horse-power.  The  weight  of 
this  propeller  is  42  pounds.  This  makes  a  total  weight 
of  motor,  complete  with  propeller,  radiator  filled  with 
water,  but  without  lubricating  oil,  755  pounds,  or  about 
5.1  pounds  per  horse-power  for  complete  power  plant. 
The  fuel  consumption  is  .5  pound  per  horse-power  per 
hour.  The  lubricating  oil  consumption  is  .0175  pound 
per  horse-power  per  hour,  or  a  total  of  2.6  pounds  per 
hour  at  1400  revolutions  per  minute.  This  would  make 
the  weight  of  fuel  and  oil,  per  hour's  run  at  full  power 
at  1400  revolutions  per  minute,  76.6  pounds. 

PKINCIPAL   DIMENSIONS 

Following  are  the  principal  dimensions  of  the  six- 
cylinder  motor: 

Bore  5  inches. 

Stroke  6%  inches. 

Crank-shaft  diameter  throughout  2  inches. 

Length  of  crank-pin  and  main  bearings  3%  inches. 

Diameter  of  valves  3  inches  (2%  inches  clear). 


Wisconsin  Aviation  Engine  537 

Lift  of  valves  y%  inch. 

Volume  of  compression  space  22  per  cent,  of  total. 

Diameter  of  wrist-pins  l%e  inches. 

Firing  order  1-4-2-6-3-5. 

The  horse-power  developed  at  1200  revolutions  per 
minute  is  130,  at  1300  revolutions  per  minute  140,  at 
1400  revolutions  per  minute  148.  1400  is  the  maximum 
speed  at  which  it  is  recommended  to  run  these  motors. 

TWELVE-CYLINDER   ENGINE 

A  twelve-cylinder  V-type  engine  illustrated,  is  also 
being  built  by  this  company,  similar  in  dimensions  of 
cylinders  to  the  six.  The  principal  differences  being  in 
the  drive  to  cam-shaft,  which  is  through  spur  gears  in- 
stead of  bevel.  A  hinged  type  of  connecting  rod  is  used 
which  does  not  increase  the  length  of  the  motor  and,  at 
the  same  time,  this  construction  provides 'for  ample  bear- 
ings. A  double  centrifugal  water  pump  is  provided  for 
this  motor,  so  as  to  distribute  the  water  uniformly  to 
both  sets  of  cylinders.  Four  magnetos  are  used,  two  for 
each  set  of  six  cylinders.  The  magnetos  are  very  acces- 
sibly located  on  a  bracket  on  the  spur  gear  cover.  The 
carburetors  are  located  on  the  outside  of  the  motors, 
where  they  are  very  accessible,  while  the  exhaust  is  in  the 
center  of  the  valley.  The  crank-shaft  on  the  twelve  is 
2y2  inches  in  diameter  and  the  shaft  is  bored  to  reduce 
weight.  Dimensioned  drawings  of  the  twelve-cylinder 
engine  are  given  at  Figs.  242  and  243  and  should  prove 
useful  for  purposes  of  comparison  with  other  motors. 

HALL-SCOTT   AVIATION   ENGINES 

The  following  specifications  of  the  Hall-Scott  "Big 
Four"  engines  apply  just  as  well  to  the  six-cylinder 
vertical  types  which  are  practically  the  same  in  construc- 
tion except  for  the  structural  changes  necessary  to  ac- 
commodate the  two  extra  cylinders.  Cylinders  are  cast 


538 


Aviation  Engines 


separately  from  a  special  mixture  of  semi-steel,  having 
cylinder  head  with  valve  seats  integral.  Special  attention 
has  been  given  to  the  design  of  the  water  jacket  around 
the  valves  and  head,  there  being  two  inches  of  water 


Tig.  242. — Dimensioned  End  View  of  Wisconsin  Twelve-Cylinder  Airplane 

Motor. 

•space  above  same.  The  cylinder  is  annealed,  rough 
machined,  then  the  inner  cylinder  wall  and  valve  seats 
ground  to  mirror  finish.  This  adds  to  the  durability  of 
the  cylinder,  and  diminishes  a  great  deal  of  the  excess 
friction. 


Hall- Scott  Engines 


539 


Great  care  is  taken  in  the  casting  and  machining  of 
these  cylinders,  to  have  the  bore  and  walls  concentric 
with  each  other.  .Small  ribs  are  cast  between  outer  and 
inner  walls  to  assist  cooling  as  well  as  to  transfer  stresses 
direct  from  the  explosion  to  hold-down  bolts  which  run 
from  steel  main  bearing  caps  to  top  of  cylinders.  The 
cylinders  are  machined  upon  the  sides  so  that  when 
assembled  on  the  crank-case  with  grooved  hold-down 


Fig.  243. — Dimensioned  Side  Elevation  of  Wisconsin  Twelve-Cylinder  Air- 
plane Motor. 

wafers  tightened,  they  form  a  solid  block,  greatly  assist- 
ing the  rigidity  of  crank-case. 

The  connecting  rods  are  very  light,  being  of  the  I 
beam  type,  milled  from  a  solid  Chrome  nickel  die  forging. 
The  caps  are  held  on  by  two  %"-20  thread  Chrome  nickel 
through  bolts.  '  The  rods  are  first  roughed  out,  then  an- 
nealed. Holes  are  drilled,  after  which  the  rods  are  hard- 
ened and  holes  ground  parallel  with  each  other.  The 
piston  end  is  fitted  with  a  gun  metal  bushing,  while  the 
crank-pin  end  carries  two  bronze  serrated  shells,  which 
are  tinned  and  babbitted  hot,  being  broached  to  harden 
the  babbitt.  Between  the  cap  and  rod  proper  are  placed 


540  Aviation  Engines 

laminated  shims  for  adjustment.  Crank-cases  are  cast  of 
the  best  aluminum  alloy,  hand  scraped  and  sand  blasted 
inside  and  out.  The  lower  oil  case  can  be  removed  with- 
out breaking  any  connections,  so  that  the  connecting  rods 
and  other  working  parts  can  readily  be  inspected.  An 
extremely  large  strainer  and  dirt  trap  is  located  in  the 
center  and  lowest  point  of  the  case,  which  is  easily  re- 
moved from  the  outside  without  disturbing  the  oil  pump 
or  any  working  parts.  A  Zenith  carburetor  is  provided. 
Automatic  valves  and  springs  are  absent,  making  the 
adjustment  simple  and  efficient.  This  carburetor  is  not 
affected  by  altitude  to  any  appreciable  extent.  A  Hall- 
Scott  device,  covered  by  U.  S.  Patent  No.  1,078,919,  allows 
the  oil  to  be  taken  direct  from  the  crank-case  and  run 
around  the  carburetor  manifold,  which  assists  carburetion 
as  well  as  reduces  crank-case  heat.  Two  waterproof  four- 
cylinder  Splitdorf  "  Dixie  "  magnetos  are  provided.  Both 
magneto  interrupters  are  connected  to  a  rock  shaft  in- 
tegral with  the  motor,  making  outside  connections  unneces- 
sary. It  is  worthy  of  note  that  with  this  independent 
double  magneto  system,  one  complete  magneto  can  become 
inoperative,  and  still  the  motor  will  run  and  continue  to 
give  good  power. 

The  pistons  as  provided  in  the  A-7  engines  are  cast 
from  a  mixture  of  steel  and  gray  iron.  These  are  ex- 
tremely light,  yet  provided  with  six  deep  ribs  under  the 
arch  head,  greatly  aiding  the  cooling  of  the  piston  as  well 
as  strengthening  it.  The  piston  pin  bosses  are  located 
very  low  in  order  to  keep  the  heat  from  the  piston  head 
away  from  the  upper  end  of  the  connecting  rod,  as  well 
as  to  arrange  them  at  the  point  where  the  piston  fits  the 
cylinder  best.  Three  ^4"  rings  are  carried.  The  pistons 
as  provided  in  the  A-7a  engines  are  cast  from  aluminum 
alloy.  Four  14"  rings  are  carried.  In  both  piston  types 
a  large  diameter,  heat  treated,  Chrome  nickel  steel  wrist- 
pin  is  provided,  assembled  in  such  a  way  as  to  assist  the 
circular  rib  between  the  wrist-pin  bosses  to  keep  the 
piston  from  being  distorted  from  the  explosions. 


Hall-Scott  Engines  541 

The  oiling  system  is  known  as  the  high  pressure  type, 
oil  being  forced  to  the  under  side  of  the  main  bearings 
with  from  5  to  30  points  pressure.  This  system  is  not 
affected  by  extreme  angles  obtained  in  flying,  or  whether 
the  motor  is  used  for  push  or  pull  machines.  A  large 
gear  pump  is  located  in  the  lowest  point  of  the  oil  sump, 
and  being  submerged  at  all  times  with  oil,  does  away 
with  troublesome  stuffing  boxes  and  check  valves.  The 
oil  is  first  drawn  from  the  strainer  in  oil  sump  to  the  long 
jacket  around  the  intake  manifold,  then  forced  to  the 
main  distributor  pipe  in  crank-case,  which  leads  to  all 
main  bearings.  A  bi-pass,  located  at  one  end  of  the 
distributor  pipe,  can  be  regulated  to  provide  any  pres- 
sure required,  the  surplus  oil  being  returned  to  the  case. 
A  special  feature  of  this  system  is  the  dirt,  water  and 
sediment  trap,  located  at  the  bottom  of  the  oil  sump. 
This  can  be  removed  without  disturbing  or  dismantling 
the  oil  pump  or  any  oil  pipes.  A  small  oil  pressure  gauge 
is  provided,  which  can 'be  run  to  the  aviator's  instrument 
board.  This  registers  the  oil  pressure,  and  also  deter- 
mines its  circulation. 

The  cooling  of  this  motor  is  accomplished  by  the  oil 
as  well  as  the  water,  this  being  covered  by  patent  No. 
1,078,919.  This  is  accomplished  by  circulating  the  oil 
around  a  long  intake  manifold  jacket;  the  carburetion 
of  gasoline  cools  this  regardless  of  weather  conditions. 
Crank-case  heat  is  therefore  kept  at  a  minimum.  The 
uniform  temperature  of  the  cylinders  is  maintained  by/ 
the  use  of  ingenious  internal  outlet  pipes,  running  through 
the  head  of  each  of  the  six-cylinders,  rubber  hose  con- 
nections being  used  so  that  any  one  of  the  cylinders  may 
be  removed  without  disturbing  the  others.  Slots  are  cut 
in  these  pipes  so  that  cooler  water  is  drawn  directly 
around  the  exhaust  valves.  Extra  large  water  jackets 
are  provided  upon  the  cylinders,  two  inches  of  water 
space  is  left  above  the  valves  and  cylinder  head.  The 
water  is  circulated  by  a  large  centrifugal  pump  insuring 
ample  circulation  at  all  speeds. 


542  Aviation  Engines 

The  crank-shaft  is  of  the  five  bearing  type,  being 
machined  from  a  special  heat  treated  drop  forging  of  the 
highest  grade  nickel  steel.  The  forging  is  first  drilled, 
then  roughed  out.  After  this  the  shaft  is  straightened, 
turned  down  to  a  grinding  size,  then  ground  accurately 
to  size.  The  bearing  surfaces  are  of  extremely  large 
size,  over-size,  considering  general  practice  in  the  build- 
ing of  high  speed  engines  of  similar  bore  and  stroke. 
The  crank-shaft  bearings  are  2"  in  diameter  by  l15Ae// 
long,  excepting  the  rear  main  bearing,  which  is  4%" 
long,  and  front  main  bearing,  which  is  2%6"  long.  Steel 
oil  scuppers  are  pinned  and  sweated  onto  the  webs  of 
the  shaft,  which  allows  of  properly  oiling  the  connecting 
rod  bearings.  Two  thrust  bearings  are  installed  on  the 
propeller  end  of  the  shaft,  one  for  pull  and  the  other  for 
push.  The  propeller  is  driven  by  the  crank-shaft  flange, 
which  is  securely  held  in  place  upon  the  shaft  by  six 
keys.  These  drive  an  outside  propeller  flange,  the  pro- 
peller being  clamped  between  them  by  six  through  bolts. 
The  flange  is  fitted  to  a  long  taper  on  crank-shaft.  This 
enables  the  propeller  to  be  removed  without  disturbing 
the  bolts.  Timing  gears  and  starting  ratchets  are  bolted 
to  a  flange  turned  integral  with  shaft. 

The  cam-shaft  is  of  the  one  piece  type,  air  pump 
eccentric,  and  gear  flange  being  integral.  It  is  made 
from  a  low  carbon  specially  heat  treated  nickel  forging, 
is  first  roughed  out  and  drilled  entire  length ;  the  cams 
are  then  formed,  after  which  it  is  case  hardened  and 
ground  to  size.  The  cam-shaft  bearings  are  extra  long, 
made  from  Parson 's  White  Brass.  A  small  clutch  is 
milled  in  gear  end  of  shaft  to  drive  revolution  indicator. 
The  cam-shaft  is  enclosed  in  an  aluminum  housing  bolted 
directly  on  top  of  all  six  cylinders,  being  driven  by  a 
vertical  shaft  in  connection  with  bevel  gears.  This  shaft, 
in  conjunction  with  rocker  arms,  rollers  and  other  work- 
ing parts,  are  oiled  by  forcing  the  oil  into  end  of  shaft, 
using  same  as  a  distributor,  allowing  the  surplus  supply 
to  flow  back  into  the  crank-case  through  hollow  vertical 


Hall-Scott  Engine  Details  543 

tube.  This  supply  oils  the  magneto  and  pump  gears. 
Extremely  large  Tungsten  valves,  being  one-half  the  cylin- 
der diameter,  are  seated  in  the  cylinder  heads.  Large 
diameter  oil  tempered  springs  held  in  tool  steel  cups, 
locked  with  a  key,  are  provided.  The  ports  are  very 
large  and  short,  being  designed  to  .allow  the  gases  to  en- 
ter and  exhaust  with  the  least  possible  resistance.  These 
valves  are  operated  by  overhead  one  piece  cam-shaft  in 
connection  with  short  Chrome  nickel  rocker  arms.  These 
arms  have  hardened  tool  steel  rollers  on  cam  end  with 
hardened  tool  steel  adjusting  screws  opposite.  This  conr 
struction  allows  accurate  valve  timing  at  all  speeds  with 
least  possible  weight. 


CENSORED 


GERMAN   AIRPLANE    MOTORS 

In  a  paper  on  "Aviation  Motors,"  presented  by  E.  H. 
Sherbondy  before  the  Cleveland  section  of  the  S.  A.  E. 
in  June,  1917,  the  Mercedes  and  Benz  airplane  motor  is 
discussed  in  some  detail  and  portions  of  the  description 
follow. 

MERCEDES    MOTOR 

The  150  horse-power  six-cylinder  Mercedes  motor  is 
140  millimeters  bore  and  160  millimeters  stroke.  The 
Mercedes  company  started  with  smaller-sized  cylinders, 
namely  100  millimeters  bore  and  140  millimeters  stroke, 
six-cylinders.  The  principal  features  of  the  design  are 
forged  steel  cylinders  with  forged  steel  elbows  for  gas 
passages,  pressed  steel  water  jackets,  which' when  welded 


544  Aviation  Engines 


CENSORED 


Argus  Engine  Construction 


545 


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Aviation  Engines 


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548  Aviation  Engines 

together  forms  the  cylinder  assembly,  the  use  of  inclined 
overhead  valves  operated  by  means  of  an  overhead  cam- 
shaft through  rocker  arms  which  multiply  with  the  mo- 
tion of  the  cam.  By  the  use  of  steel  cylinders,  not  only 
is  the  weight  greatly  reduced,  but  certain  freedom  from 
distortion  through  unequal  sections,  leaks  and  cracks  are 
entirely  avoided.  The  construction  is  necessarily  very 
expensive.  It  is  certainly  a  sound  job.  In  the  details 
of  this  construction  there  are  a  number  of  important 
things,  such  as  finished  gas  passages,  water-cooled  valve 
guides  and  a  very  small  mass  of  metal,  which  is  water- 
cooled,  surrounding  the  spark-plug.  Of  course,  it  is  nec- 
essary to  use  very  high  compression  in  aviation  motors 
in  order  to  secure  high  power  and  economy  and  owing  to 
the  fact  that  aviation  motors  are  worked  at  nearly  their 
maximum,  the  heat  flow  through  the  cylinder,  piston,  and 
valves  is  many  times  higher  than  that  encountered  in 
automobile  motors.  It  has  been  found  necessary  to  de- 
velop -special  types  of  pistons  to  carry  the  heat  from  the 
center  of  the  head  in  order  to  prevent  pre-ignition.  In 
the  Mercedes  motor  the  pistons  have  a  drop  forged  steel 
head  which  includes  the  piston  boss  and  this  head  is 
screwed  into  a  cast  iron  skirt  which  has  been  machined 
inside  to  secure  uniform  wall  thickness. 

The  carburetor  used  on  this  150  horse-power  Mer- 
cedes motor  is  precisely  of  the  same  type  used  on  the 
Twin  Six  motor.  It  has  two  venturi  throats,  in  the  center 
of  which  is  placed  the  gasoline  spray  nozzle  of  conven- 
tional type,  fixed  size  orifices,  immediately  above  which 
are  placed  two  panel  type  throttles  with  side  outlets. 
An  idling  or  primary  nozzle  is  arranged  to  discharge 
above  the  top  of  the  venturi  throat.  The  carburetor 
body  is  of  cast  aluminum  and  is  water  jacketed.  It  is 
bolted  directly  to  air  passage  passing  through  the  top 
and  bottom  half  of  the  crank-case  which  passes  down 
through  the  oil  reservoir.  The  air  before  reaching  the 
carburetor  proper  to  some  extent  has  cooled  the  oil  in 
the  crank  chamber  and  has  itself  been  heated  to  assist 


Mercedes  Engine  Details 


549 


in  the  vaporization.  The  inlet  pipes  themselves  are  cop- 
per. All  the  passages  between  the  venturi  throat  and 
the  inlet  valve  have  been  carefully  finished  and  polished. 
The  only  abnormal  thing  in  the  design  of  this  motor  is 
the  short  connecting  rod  which  is  considerably  less  than 
twice  the  stroke  and  would  be  considered  very  bad  practice 
in  motor  car  engines.  A  short  connecting  rod,  however, 


Fig.  245. — Part  Sectional  View  of  90  Horse-Power  Mercedes  Engine* 
Which  is  Typical  of  the  Design  of  Larger  Sizes. 


possesses  two  very  real  virtues  in  that  it  cuts  down  height 
of  the  motor  and  the  piston  passes  over  the  bottom  dead 
center  much  more  slowly  than  with  a  long  rod. 

Other  features  of  the  design  are  a  very  stiff  crank- 
case,  both  halves  of  which  are  bolted  together  by  means 
of  long  through  bolts,  the  crank- shaft  main  bearings  are 
seated  in  the  lower  half  of  the  case  instead  of  in  the 
usual  caps  and  no  provision  is  made  for  taking  up  the 
main  bearings.  The  Mercedes  company  uses  a  plunger 


550  Aviation  Engines 

type  of  pump  having  mechanically  operated  piston  valves 
and  it  is  driven  by  means  of  worm  gearing. 

The  overhead  cam-shaft  construction  is  extremely 
light.  The  cam-shaft  is  mounted  in  a  nearly  cylindrical 
cast  bronze  case  and  is  driven  by  means  of  bevel  gears 
from  the  crank-shaft.  The  vertical  bevel  gear  shaft 
through  which  the  drive  is  taken  from  the  crank- shaft  to 
the  cam-shaft  operates  at  one  and  one-half  times  the 
crank-shaft  speeds  and  the  reduction  to  the  half-time 
cam-shaft  is  secured  through  a  pair  of  bevels.  On  this 
vertical  shaft  there  is  mounted  the  water  pump  and  a 
bevel  gear  for  driving  two  magnetos.  The  water  pump 
mounted  on  this  shaft  tends  to  steady  the  drive  and  avoid 
vibration  in  the  gearing. 

The  cylinder  sizes  of  six-cylinder  aviation  motors 
which  have  been  built  by  Mercedes  are 

Bore  Stroke  Horse-power 

105  mm.  140  mm.  100 

120  mm.  140  mm.  135 

140  mm.  150  mm.  150 

140  mm.  160  mm.  160 

The  largest  of  these  motors  has  recently  had  its  horse- 
power increased  to  176  at  1450  K.  P.  M.  This  general 
design  of  motor  has  been  the  foundation  for  a  great  many 
other  aviation  motor  designs,  some  of  which  have  proved 
very  successful  but  none  of  which  is  equal  to  the  origi- 
nal. Among  the  motors  which  follow  more  or  less  closely 
the  scheme  of  design  and  arrangement  are  the  Hall-Scott, 
the  "Wisconsin  motor,  the  Eenault  water-cooled,  the  Pack- 
ard, the  Christofferson  and  the  Eolls-Koyce.  Each  of 
these  motors  show  considerable  variation  in  detail.  The 
Kolls-Eoyce  and  Eenault  are  the  only  ones  who  have  used 
the  steel  cylinder  with  the  steel  jacket.  The  Wisconsin 
motor  uses  an  aluminum  cylinder  with  a  hardened  steel 
liner  and  cast-iron  valve  seats.  The  Christofferson  has 
somewhat  similar  design  to  the  Wisconsin  with  the  ex- 
ception that  the  valve  seats  are  threaded  into  the  alumi- 


The  Benz  Motor  551 

num.  jacket  and  the  cylinder  head  has  a  blank  end  which 
is  secured  to  the  aluminum  casting  by  means  of  the  valve 
seat  pieces.  The  Eolls-Koyce  motors  show  small  differ- 
ences in  details  of  design  in  cylinder  head  and  cam-shaft 
housing  from  the  Mercedes  on  which  it  has  taken  out 
patents,  not  only  abroad  but  in  this  country. 

THE   BE^Z    MOTOR 

In  the  Kaiser  prize  contest  for  aviation  motors  a  four- 
cylinder  Benz  motor  of  130  by  180  mm.  won  first  prize, 
developing  103  B.  H.  P.  at  1290  R.  P.  M.  The  fuel  con- 
sumption was  210  grams  per  horse-power  hour.  Total 
weight  of  the  motor  was  153  kilograms.  The  oil  con- 
sumption was  .02  of  a  kilogram  per  horse-power  hour. 
•This  motor  was  afterward  expanded  into  a  six-cylinder 
design  and  three  different  sizes  were  built. 

The  accompanying  table  gives  some  of  the  details  of 
weight,  horse-power,  etc. 

Motor  type B  FD  FF 

Rated  horse-power 85  100  150 

Horse-power  at  1250  r.p.m 88  108  150 

Horse-power  at  1350  r.p.m 95  115  160 

Bore  in  millimeters 106  116  130 

Stroke  in  millimeters 150  160  180 

Offset  of  the  cylinders  in  millimeters 18  20  20 

Rate  of  gasoline  consumption  in  grams 240  230  225 

Oil  consumption  in  grams  per  b.h.p.  hour 10  10  10 

Oil  capacity  in  kilo'grams 36  4  4% 

Water  capacity  in  litres 5  %  7  %  9  y2 

The  weight  with  water  and   oil  but  with   two 

magnetos,    fuel    feeder   and    air   pump    in 

kilograms 170  200  245 

The   weight    of    motors,    including    the   water 

pump,  two  magnetos,  double  ignition,  etc. .  160  190  230 
The  weight  of  the   exhaust  pipe,   complete  in 

kilograms 4  4.8  5  % 

The  weight  of  the  propeller  hub  in  kilograms .  3^4  4 

The  Benz  cylinder  is  a  simple,  straightforward  design 
and  a  very  reliable  construction  and  not  particularly  diffi- 
cult to  manufacture.  The  cylinder  is  cast  of  iron  without 


552  Aviation  Engines 

a  water  jacket  but  including  45  degrees  angle  elbows  to 
the  valve  ports.  The  cylinders  are  machined  wherever 
possible  and  at  other  points  have  been  hand  filed  and 
scraped,  after  which  a  jacket,  which  is  pressed  in  two 
halves,  is  gas  welded  by  means  of  short  pipes  welded  on 
to  the  jacket.  The  bottom  and  the  top  of  the  cylinders 
become  water  galleries,  and  by  this  means  separate  water 
pipes  with  their  attendant  weight  and  complication  are 
eliminated.  Eubber  rings  held  in  aluminum  clamps  serve 
to  connect  the  cylinders  together.  The  whole  construc- 
tion turns  out  very  neat  and  light.  The  cylinder  walls 
are  4  mm.  or  %_$"  thick  and  the  combustion  chamber  is  of 
cylindrical  pancake  form  and  is  140  mm.  or  5.60  inch  in 
diameter.  The  valve  seats  are  68  mm.  in  diameter  and 
the  valve  port  is  62  mm.  in  diameter. 

The  passage  joining  the  port  is  57  mm.  in  diameter. 
In  order  to  insert  the  valves  into  the  cylinder  the  valve 
stem  is  made  with  two  diameters  and  the  valve  has  to 
be  cocked  to  insert  it  in  the  guide,  which  has  a  bronze 
bushing  at  its  upper  end  to  compensate  for  the  smaller 
valve  stem  diameter.  The  valve  stem  is  14  mm.  or  %G" 
in  diameter  and  is  reduced  at  its  upper  portion  to  9y2  mm. 
The  valves  are  operated  through  a  push  rod  and  rocker 
arm  construction,  which  is  %6"  and  exceedingly  light. 
Kocker  arm  supports  are  steel  studs  with  enlarged  heads 
to  take  a  double  row  ball  bearing.  A  roller  is  mounted 
at  one  end  of  the  rocker  arm  to  impinge  on  the  end  of 
the  valve  stem,  and  the  rocker  arm  has  an  adjustable 
globe  stud  at  the  other  end.  The  push  rods  are  light  steel 
tubes  with  a  wall  thickness  of  0.75  mm.  and  have  a  hard- 
ened steel  cup  at  their  upper  end  to  engage  the  rocker 
arm  globe  stud  and  a  hardened  steel  globe  at  their  lower 
end  to  socket  in  the  roller  plunger. 

The  Benz  cam-shaft  has  a' diameter  of  26  mm.  and  is 
bored  straight  through  18  mm.  and  there  is  a  spiral  gear 
made  integrally  with  the  shaft  in  about  the  center  of  its 
length  for  driving  the  oil  pump  gear.  '  The  cam  faces  are 
10  mm.  wide.  There  is  also,  in  addition  to  the  intake 


The  Benz  Motor  553 

and  exhaust  cams,  a  set  of  half  compression  cams.  The 
shaft  is  moved  longitudinally  in  its  bearings  by  means  of 
an  eccentric  to  put  these  cams  into  action.  At  the  fore 
end  of  the  shaft  is  a  driving  gear  flange  which  is  very 
small  in  diameter  and  very  thin.  The  flange  is  68  mm. 
in  diameter  and  4  mm.  thick  and  is  tapped  to  take  6  mm. 
bolts.  The  total  length  of  cam-shaft  is  1038  mm.,  and  it 
becomes  a  regular  gun  boring  job  to  drill  a  hole  of  this 
length. 

The  cam-shaft  gear  is  140  mm.  or  5%  inches  outside 
diameter.  It  has  fifty-four  teeth  and  the  gear  face  is  15 
mm.  or  1%2/'.  The  flange  and  web  have  an  average  thick- 
ness of  4  mm.  or  %2r/  ancj,  the  web  is  drilled  full  of  holes 
interposed  between  the  spur  gear  mounted  on  the  cam- 
shaft and  the  cam-shaft  gear.  There  is  a  gear  which 
serves  to  drive  the  magnetos  and  tachometer,  also  the 
air  pump.  The  shaft  is  made  integrally  with  this  gear 
and  has  an  eccentric  portion  against  which  the  air  pump 
roll  plunger  impinges. 

•  The  seven-bearing  crank-shaft  is  finished  all  over  in 
a  beautiful  manner,  and  the  shaft  out  of  the  particular 
motor  we  have  shows  no  signs  of  wear  whatever.  The 
crank-pins  are  55  mm.  in  diameter  and  69  mm.  long. 
Through  both  the  crank-pin  and  main  bearings  there  is 
drilled  a  28  mm.  hole,  and  the  crank  cheeks  are  plugged 
with  solder.  The  crank  cheeks  are  also  built  to  convey 
the  lubricant  to  the  crank-pins.  At  the  fore  end  of  the 
crank  cheek  there  is  pressed  on  a  spur  driving  gear. 
There  is  screwed  on  to  the  front  end  of  the  shaft  a  piece 
which  forms  a  bevel  water  pump  driving  gear  and  the 
starting  dog.  At  the  rear  end  of  the  shaft  very  close  to 
the  propeller  hub  mounting  there  is  a  double  thrust  bear- 
ing to  take  the  propeller  thrust. 

Long,  shouldered  studs  are  screwed  into  the  top  half 
of   the   crank-case   portion   of   the   case   and   pass   clean 
x  through  the  bottom  half  of  the  case.     The  case  is  very 
stiff   and   well   ribbed.      The    three    center   bearing    dia- 
phragms have  double  walls.     The  center  one  serves  as  a 


554  Aviation  Engines 

duct  through  which  water  pipe  passes,  and  those  on  either 
side  of  the  center  form  the  carburetor  intake  air  passages 
and  are  enlarged  in  section  at  one  side  to  take  the  car- 
buretor barrel  throttle. 

The  pistons  are  of  cast  iron  and  carry  three  concentric 
rings  1/4  inch  wide  on  their  upper  end,  which  are  pinned 
at  the  joint.  The  top  of  the  piston  forms  the  frustum 
of  the  cone  and  the  pistons  are  110  mm.  in  length.  The 
lower  portion  of  the  skirt  is  machined  inside  and  has  a 
wall  thickness  of  1  mm.  Kiveted  to  the  piston  head  is 
a  conical  diaphragm  which  contacts  with  the  piston  pin 
when  in  place  and  serves  to  carry  the  heat  off  the  center 
of  the  piston. 

The  oil  pump  assembly  comprises  a  pair  of  plunger 
pumps  which  draw  oil  from  a  separate  outside  pump,  and 
constructed  integrally  with  it  is  a  gear  pump  which  de- 
livers the  oil  under  about  60  pound  pressure  through  a 
set  of  copper  pipes  in  the  base  to  the  main  bearings.  The 
plunger  oil  pump  shows  great  refinement  of  detail.  A 
worm  wheel  and  two  eccentrics  are  machined  up  out  of 
one  piece  and  serve  to  operate  the  plungers. 

Some  interesting  details  of  the  160  horse-power  Benz 
motor,  which  is  shown  at  Fig.  246,  are  reproduced  from 
the  "Aerial  Age  Weekly,"  and  show  how  carefully  the 
design  has  been  considered. 

Maximum  horse-power,  167.5  B.  H.  P. 

Speed  at  maximum  horse-power,  1,500  E.  P.  M. 

Piston  speed  .at  maximum  horse-power,  1,770  ft.  per 
minute. 

Normal  horse-power,  160  B.  H.  P. 

Speed  at  normal  horse-power,  1,400  E.  P.  M. 

Piston  speed  at  normal  horse-power,  1,656  ft.  per 
minute. 

Brake  mean  pressure  at  maximum  horse-power,  101.2 
pound  per  square  inch. 

Brake  mean  pressure  at  normal  horse-power,  103.4 
pound  per  square  inch. 


The  Benz  Motor 


555 


556  Aviation  Engines 

Specific  power  cubic  inch  swept  volume  per  B.  H.  P., 
5.46  cubic  inch;  160  B.  H.  P. 

Weight  of  piston,  complete  with  gudgeon  pin,  rings, 
etc.,  5.0  pound. 

Weight    of   connecting    rod,    complete    with   bearings, 
4.99  pound;  1.8  pound  reciprocating. 

Weight  of  reciprocating  parts  per  cylinder,  6.8  pound. 

Weight    of    reciprocating    parts    per    square    inch    of 
piston  area,  0.33  pound. 

Outside  diameter  of  inlet  valve,  68  mm.;  2.68  inches. 

Diameter  of  inlet  valve  port  (d),  61.5  mm.;  2.42  inches. 

Maximum  lift  of  inlet  valve  (7&),  11  mm.,  0.443  inch. 

Area  of  inlet  valve  opening  (ndh),  21.25  square  cm.; 
3.29  square  inches. 

Inlet  valve  opens,  degrees  on  crank,  top  dead  center. 

Inlet  valve  closes,  degrees  on  crank,  60°  late;  35  mm. 
late. 

Outside  diameter  of  exhaust  valve,  68  mm.,  2.68  inches. 

Diameter  of  exhaust  valve  port    (cZ),  61.5  mm.;  2!42 
inches. 

Maximum  lift   or   exhaust   valve  '(h)    11   mm.;   0.433 
inch. 

Area  of  exhaust  valve  opening   (ndJi),  21.25  square 
cm.;  3.29  square  inches. 

Exhaust   valve   opens,   degrees   on   crank,   60°    early; 
35  mm.  early. 

Exhaust  valve  closes,  degrees   on  crank,   16%°   late; 
5  mm.  late. 

Length  of  connecting  rod  between  centers,  314  mm.; 
12.36  inches. 

Eatio  connecting  rod  to  crank  throw,  3.49:1. 

Diameter  of  crank-shaft,  56  mm.  outside,  2.165  inches; 
28  mm.  inside,  1.102  inches. 

Diameter  of  crank-pin,  55  mm.  outside,  2.165  inches; 
28  mm.  inside,  1.102  inches. 

Diameter  of  gudgeon  pin,  30  mm.  outside,  1.181  inches ; 
19  mm.  inside,  0.708  inch. 


Austro-Dcdmler  Engine  557 

Diameter  of  cam-shaft,  26  nun.  outside,  1.023  inches ; 
18  mm.  inside,  0.708  inch. 

Number  of  crank-shaft  bearings,  7. 

Projected  area  of  crank-pin  bearings,  36.85  square 
cm.;  5.72  square  inches. 

Projected  area  of  gudgeon  pin  bearings,  22.20  square 
cm.;  3.44  square  inches. 

Firing  sequence,  1,  5,  3,  6,  2,  4. 

Type  of  magnetos,  ZH6  Bosch. 

Direction  of  rotation  of  magneto  from  driving  end, 
one  clock,  one  anti-clock. 

Magneto  timing,  full  advance?  30°  early  (16  mm. 
early). 

Type  of  carburetors  (2)  Benz  design. 

Fuel  consumption  per  hour,  normal  horse-power,  0.57 
pint. 

Normal  speed  of  propeller,  engine  speed,  1,400  E.  P.  M. 

AUSTRO-DAIMLER   ENGINE 

One  of  the  first  very  successful  European  flying  engines 
which  was  developed  in  Europe  is  the  Austro-Daimler, 
which  is  shown  in  end  section  in  a  preceding  chapter.  The 
first  of  these  motors  had  four-cylinders,  120  by  140  milli- 
meters, bore  and  stroke,  with  cast  iron  cylinders,  over- 
head valves  operated  by  mean's  of  a  single  rocker  arm, 
controlled  by  two  cams  and  the  valves  were  closed  by  a 
single  leaf  spring  which  oscillates  with  the  rocker  arm. 
The  cylinders  are  cast  singly  and  have  either  copper  or 
steel  jackets  applied  to  them.  The  four-cylinder  design 
was  afterwards  expanded  to  the  six-cylinder  design  and 
still  later  -a  six-cylinder  motor  of  130  by  175  millimeters 
was  developed.  This  motor  uses  an  offset  crank-shaft, 
as  does  the  Benz  motor,  and  the  effect  of  offset  has  been 
discussed  earlier  on  in  this  treatise.  The  Benz  motor  also 
uses  an  offset  cam-shaft  which  improves  the  valve  opera- 
tion and  changes  the  valve  lift  diagram.  The  lubrication 
also  is  different  than  any  other  aviation  motor,  since 


558  Aviation  Engines 

individual  high  pressure  metering  pumps  are  used  to 
deliver  fresh  oil  only  to  the  bearings  and  cylinders,  as 
was  the  custom  in  automobile  practice  some  ten  years  .ago. 


SUNBEAM   AVIATION   ENGINES 

These  very  successful  engines  have  been  developed  by 
Louis  Coatalen.  At  the  opening  of  the  war  the  largest 
sized  Coatalen  motor  was  225  horse-power  and  was  of  the 
L-head  type  having  a  single  cam-shaft  for  operating 
valves  and  was  an  evolution  from  the  twelve-cylinder 
racing  car  which  the  -Sunbeam  Company  had  previously 
built.  Since  1914  the  Sunbeam  Company  have  produced 
engines  of  six-,  eight-,  twelve-  and  eighteen-cylinders  from 
150  to  500  horse-power  with  both  iron  and  aluminum 
cylinders.  For  the  last  two  years  all  the  motors  have  had 
overhead  cam-shafts  with  a  separate  shaft  for  operating 
the  intake  and  exhaust  valves.  Cam-shafts  are  connected 
through  to  the  crank-shaft  by  means  of  a  train  of  spur 
gears,  all  of  which  are  mounted  on  two  double  row  ball 
bearings.  In  the  twin  six,  350  horse-power  engine,  oper- 
ating at  2100  E.  P.  M.,  requires  about  4  horse-power 
to  operate  the  cam-shafts.  This  motor  gives  362  horse- 
power at  2100  revolutions  and  has  a  fuel  cousumption  of 
5Koo  of  a  pint  per  brake  horse-power  hour.  The  cylinders 
are  110  by  160  millimeters.  The  same  design  has  been 
expanded  into  an  eighteen-cylinder  which  gives  525  horse- 
power at  2100  turns.  There  has  also  been  developed  a 
very  successful  eight-cylinder  motor  rated  at  2220  horse- 
power which  has  a  bore  and  stroke  of  120  by  130  milli- 
meters, weight  450  pounds.  This  motor  is  an  aluminum 
block  construction  with  steel  sleeves  inserted.  Three 
valves  are  operated,  one  for  the  inlet  and  two  for  the 
exhaust.  One  cam-shaft  operates  the  three  valves. 

The  modern  Sunbeam  engines  operate  with  a  mean 
effective  pressure  of  135  pounds  with  a  compression  ratio 
of  6  to  1  sea  level.  The  connecting  rods  are  of  the  articu- 
lated type  as  in  the  Eenault  motor  and  are  very  short. 


Sunbeam  Aviation  Engines 


559 


The  weight  of  these  motors  turns  out  at  2.6  pounds  per 
brake  horse-power,  and  they  are  able  to  go  through  a 
100  hour  test  without  any  trouble  of  any  kind.  The  lubri- 
cating system  comprises  a  dry  base  and  oil  pump  for. 


Fig.  247. — At  Top,  the  Sunbeam  Overhead  Valve  170  Horse-Power  Six- 
Cylinder  Engine.  Below,  Side  View  of  Sunbeam  350  Horse-Power 
Twelve-Cylinder  Vee  Engine. 

drawing  the  oil  off  from  the  base,  whence  it  is  delivered 
to  the  filter  and  cooling  system.  It  then  is  pumped  by  a 
separate  high  pressure  gear  pump  through  the  entire 
motor.  In  these  larger  European  motors,  castor-oil  is 


560 


Aviation  Engines 


Sunbeam  Aviation  Engines 


561 


used  largely  for  lubrication.  It  is  said  that  without  the 
use  of  castor-oil  it  is  impossible  to  hold  full  power  for 
five  hours.  Coatalen  favors  aluminum  cylinders  rather 
than  cast  iron.  The  series  of  views  in  Figs.  247  to  250 
inclusive,  illustrates  the  vertical,  narrow  type  of  engine; 
the  V-form;  and  the  broad  arrow  type  wherein  three 


v 


Fig.  249. — Sunbeam  Eighteen-Cylinder  Motor,  Viewed  from  Pump  and 

Magneto  End. 

rows,  each  of  six-cylinders,  are  set  on  a  common  crank- 
case.  In  this  water-cooled  series  the  gasoline  and  oil 
consumption  are  notably  low,  as  is  the  weight  per  horse- 
power. 

In  the  eighteen-cylinder  overhead  valve  Sunbeam- 
Coatalen  aircraft  engine  of  475  brake  horse-power,  there 
are  no  fewer  than  half  a  dozen  magnetos.  Each  magneto 
is  inclosed.  Two  sparks  are  furnished  to  each  cylinder 


562- 


Aviation  Engines 


from  independent  magnetos.  On  this  engine  there  are 
also  no  fewer  than  six  carburetors.  Shortness  of  crank- 
shaft, and  therefore  of  engine  length,  and  absence  of 
vibration  are  achieved  by  the  linking  of  the  connecting- 
rods.  Those  concerned  with  three-cylinders  in  the  broad 
arrow  formation  work  on  one  crank-pin,  the  outer  rods 
being  linked  to  the  central  master  one.  In  consequence 


Fig.  250. — Propeller  End  of  Sunbeam  Eighteen-Cylinder  475  B.H.P. 
Aviation  Engine. 

of  this  arrangement,  the  piston  travel  in  the  case  of  the 
central  row  of  cylinders  is  160  mm.,  while  the  stroke  of 
the  pistons  of  the  cylinders  set  on  either  side  is  in  each 
case  168  mm.  Inasmuch  as  each  set  of  six-cylinders  is 
completely  balanced  in  itself,  this  difference  in  stroke 
does  not  affect  the  balance  of  the  engine  as  a  whole.  The 


Indicating  Meters  563 

duplicate  ignition  scheme  also  applies  to  the  twelve- 
cylinder  350  brake  horse-power  Sunbeam- Coatalen  over- 
head valve  aircraft  engine  type.  It  is  distinguishable, 
incidentally,  by  the  passage  formed  through  the  center  of 
each  induction  pipe  for  the  sparking  plug  in  the  center 
cylinder  of  each  block  of  three.  In  this,  as  in  the  eighteen- 
cylinder  and  the  six-cylinder  types,  there  are  two  cam- 
shafts, for  each  set  of  cylinders.  These  cam-shafts  are 
lubricated  by  low  pressure  and  are  operated  through  a 
train  of  inclosed  spur  wheels  at  the  magneto  end  of  the 
machine.  The  six-cylinder,  170  brake  horse-power  vertical 
type  employs  the  same  general  principles,  including  the 
detail  that  each  carburetor  serves  gas  to  a  group  of  three- 
cylinders  only.  It  will  be  observed  that  this  engine  pre- 
sents notably  little  head  resistance,  being  suitable  for 
multi-engined  aircraft. 

INDICATING   METERS   FOR   AUXILIARY   SYSTEMS 

The  proper  functioning  of  the  power  plant  and  the 
various  groups  comprising  it  may  be  readily  ascertained 
at  any  time  by  the  pilot  because  various  indicating  meters 
and  pressure  gauges  are  provided  which  are  located  on  a 
dash  or  cowl  board  in  front  of  the  aviator,  as  shown  at 
Fig.  251.  The  speed  indicator  corresponds  to  the  speedom- 
eter of  an  automobile  and  gives  an  indication  of  the  speed 
the  airplane  is  making,  which  taken  in  conjunction"  with  the 
clock  will  make  it  possible  to  determine  the  distance  cov- 
ered at  a  flight.  The  altimeter,  which  is  an  aneroid 
barometer,  outlines  with  fair  accuracy  the  height  above 
the  ground  at  which  a  plane  is  flying.  These  instruments 
are  furnished  to  enable  the  aviator  to  navigate  the  air- 
plane when  in  the  air,  and  if  the  machine  is  to  be  used 
for  cross-country  flying,  they  may  be  supplemented  by  a 
compass  and  a  drift  set.  It  will  be  evident  that  these, 
are  purely  navigating  instruments  and  only  indicate  the 
motor  condition  in  an  indirect  manner.  The  best  way  of 
keeping  track  of  the  motor  action  is  to  watch  the  tachom- 


564 


Aviation  Engines 


Compressed  Air-Starting  Systems  565 

eter  or  revolution  counter  which  is  driven  from  the 
engine  by  a  flexible  shaft.  This  indicates  directly  the 
number  of  revolutions  the  engine  is  making  per  minute 
and,  of  course,  any  slowing  up  of  the  engine  in  normal 
flights  indicates  that  something  is  not  functioning  as  it 
should.  The  tachometer  operates  on  the  same  principle 
as  the  speed  indicating  device  or  speedometer  used  in 
automobiles  except  that  the  dial  is  calibrated  to  show 
revolutions  per  minute  instead  of  miles  per  hour.  At  the 
extreme  right  of  the  dash  at  Fig.  251  the  spark  advance 
and  throttle  control  levers  are  placed.  These,  of  course, 
regulate  the  motor  speed  just  as  they  do  in  an  automobile. 
Next  to  the  engine  speed  regulating  levers  is  placed  a 
push  button  cut-out  switch  to  cut  out  the  ignition  and 
stop  the  motor.  Three  pressure  gauges  are  placed'  in  a 
line.  The  one  at  the  extreme  right  indicates  the  pressure 
of  air  on  the  fuel  when  a  pressure  feed  system  is  used. 
The  middle  one  shows  oil  pressure,  while  that  nearest 
the  center  of  the  dash  board  is  employed  to  show  the  air 
pressure  available  in  the  air  starting  system.  It  will  be 
evident  that  the  character  of  the  indicating  instruments 
will  vary  with  the  design  of  the  airplane.  If  it  was  pro- 
vided with  an  electrical  starter  instead  of  an  air  system 
electrical  indicating  instruments  would  have  to  be  pro- 
vided. 

COMPRESSED   AIR- STARTING    SYSTEMS 

Two  forms  of  air- starting  systems  are  in  general  use, 
one  in  which  the  crank-shaft  is  turned  by  means  of  an 
air  motor,  the  other  class  where  compressed  air  is  ad- 
mitted to  the  cylinders  proper  and  the  motor  turned  over 
because  of  the  air  pressure  acting  on  the  engine  pistons. 
A  system  known  as  the  "Never-Miss"  utilizes  a  small 
double-cylinder  air  pump  is  driven  from  the  engine  by 
means  of  suitable  gearing  and  supplies  air  to  a  substan- 
tial container  located  at  some  convenient  point  in  the 
fuselage.  The  air  is  piped  from  the  container  to  a  dash- 
control  valve  and  from  this  member  to  a  peculiar  form 


566  Aviation  Engines 

of  air  motor  mounted  near  the  crank-shaft.  The  air 
motor  consists  of  a  piston  to  which  a  rack  is  fastened 
which  engages  a  gear  mounted  •  on  the  crank  shaft  pro- 
vided with  some  form  of  ratchet  clutch  to  permit  it  to 
revolve  only  in  one  direction,  and  then  only  when  the 
gear  is  turning  faster  than  the  engine  crank-shaft. 

The  method  of  operation  is  extremely  simple,  the 
dash-control  valve  admitting  air  from  the  supply  tank 
to  the  top  of  the  pump  cylinder.  When  in  the  position 
shown  in  cut  the  air  pressure  will  force  the  piston  and 
rack  down  and  set  the  engine  in  motion.  A  variety  of 
air  motors  are  used  and  in  some  the  pump  and  motor  may 
be  the  same  device,  means  being  provided  to  change  the 
pump  to  an  air  motor  when  the  engine  is  to  be  turned-  over. 

The  "Christensen"  air  starting  system  is  shown  at 
Figs.  252  and  253.  An  air  pump  is  driven  by  the  engine, 
and  this  supplies  air  to  an  air  reservoir  or  .container 
attached  to  the  fuselage.  This  container  communicates 
with  the  top  of  an  air  distributor  when  a  suitable  control 
valve  is  open.  An  air  pressure  gauge  is  provided  to 
enable  one  to  ascertain  the  air  pressure  available.  The 
top  of  each  cylinder  is  provided  with  a  check  valve, 
through  which  air  can  flow  only  in  one  direction,  i.e.,  from 
the  tank  to  the  interior  of  the  cylinder.  Under  explosive 
pressure  these  check  valves  close.  The  function  of  the 
distributor  is  practically  the  same  as  that  of  an  ignition 
timer,  its  purpose  being  to  distribute  the  air  to  the  cylin- 
ders of  the  engine  only  in  the  proper  firing  order.  All 
the  while  that  the  engine  is  running  and  the  car  is  in 
motion  the  air  pump  is  functioning,  unless  thrown  out  of 
action  by  an  easily  manipulated  automatic  control.  When 
it  is  desired  to  start  the  engine  a  starting  valve  is  opened 
which  permits  the  air  to  flow  to  the  top  of  the  distributor, 
and  then  through  a  pipe  to  the  check  valve  on  top  of  the 
cylinder  about  to  explode.  As  the  air  is  going  through 
under  considerable  pressure  it  will  move  the  piston  down 
just  ias  the  explosion  would,  and  start  the  engine  rotating. 
The  inside  of  the  distributor  rotates  and  directs  a  charge 


Air-Starting  System 


567 


of  air  to  the  cylinder  next  to  fire.  In  this  way  the  engine 
is  given  a  number  of  revolutions,  and  finally  a  charge  of 
gas  will  be  ignited  and  the  engine  start  off  on  its  cycle  of 
operation.  To  make  starting  positive  and  easier  some 


Fig.  252. — Parts  of  Christensen  Air  Starting  System  Shown  at  A,  and 
Application  of  Piping  and  Check  Valves  to  Cylinders  of  Thomas- 
Morse  Aeromotor  Outlined  at  B. 

gasoline  is  injected  in  with  the  air  so  an  inflammable  mix- 
ture is  present  in  the  cylinders  instead  of  air  only.  This 
ignites  easily  and  the  engine  starts  off  sooner  than  would 
otherwise  be  the  case.  The  air  pressure  required  varies 
from  125  to  250  pounds  per  square  inch,  depending  upon 
the  size  and  type  of  the  engine  to  be  set  in  motion. 


568 


Aviation  Engines 


02 
bO 

•I 

I 

CO 


Electric  Starting  Systems  569 

ELECTEIC    STARTING   SYSTEMS 

Starters  utilizing  electric  motors  to  turn  over  the 
engine  have  been  recently  developed,  and  when  properly 
made  and  maintained  in  an  efficient  condition  they  an-' 
rfwer  all  the  requirements  of  an  ideal  starting  device. 
The  capacity  is  very  high,  as  the  motor  may  draw  cur- 
rent from  a  storage  battery  and  keep  the  engine  turning 
over  for  considerable  time  on  «a  charge.  The  objection 
against  their  use  is  that  it  requires  considerable  compli- 
cated and  costly  apparatus  which  is  difficult  to  under- 
stand and  which  requires  the  services  of  an  expert  electri- 
cian to  repair  should  it  get  out  of  order,  though  if  bat- 
tery ignition  is  used  the  generator  takes  the  place  of  the 
usual  ignition  magneto. 

In  the  Delco  system  the  electric  current  is  generated 
by  a  combined  motor-generator  permanently  geared  to 
the  engine.  When  the  motor  is  running  it  turns  the 
armature  and  the  motor  generator  is  acting  as  a  dynamo, 
only  supplying  current  to  a  storage  battery.  On  account 
of  the  varying  speeds  of  the  generator,  which  are  due  to 
the  fluctuation  in  engine  speed,  some  form  of  automatic 
switch  w^hich  will  disconnect  the  generator  from  the  bat- 
tery at  such  times  that  the  motor  speed  is  not  sufficiently 
high  to  generate  a  current  stronger  than  that  delivered 
by  the  battery  is  needed.  These  automatic  switches  are 
the  only -delicate  part  of  the  entire  apparatus,  and  while 
they  requir.e  very  delicate  adjustment  they  seem  to  per- 
form very  satisfactorily  in  practice. 

When  it  is  desired  to  start  the  engine  an  electrical 
connection  is  established  between  the  storage  battery  and 
the  motor-generator  unit,  and  this  acts  as  a  motor  and 
turns  the  engine  over  by  suitable  gearing  which  engages 
the  gear  teeth  cut  into  a  special  gear  or  disc  attached  to 
the  engine  crank-shaft.  When  the  motor-generator  fur- 
nishes current  for  ignition  as  well  as  for  starting  the 
motor,  the  fact  that  the  current  can  be  used  for  this  work 
as  well  as  starting  justifies  to  a  certain  extent  the  rather 


570  Aviation  Engines 

complicated  mechanism  which  forms  a  complete  starting 
and  ignition  system,  and  which  may  also  be  used  for  light- 
ing if  necessary  in  night  flying. 

An  electric  generator  and  motor  do  not  complete  a 
self-starting  system,  because  some  reservoir  or  container 
for  electric  current  must  be  provided.  The  current  from 
the  generator  is  usually  stored  in  a  storage  battery  from 
which  it  can  be  made  to  return  to  the  motor  or  to  the 
same  armature  that  produced  it.  The  fundamental  units 
of  a  self-starting  system,  therefore,  are  a  generator  to 
produce  the  electricity,  a  storage  battery  to  serve  as  a 
reservoir,  and  an  electric  motor  to  rotate  the  motor  crank- 
shaft. Generators  are  usually  driven  by  enclosed  gear- 
ing, though  silent  chains  are  used  where  the  center  dis- 
tance between  the  motor  shaft  and  generator  shaft  is  too 
great  for  the  gears.  An  electric  starter  may  be  directly 
connected  to  the  gasoline  engine,  as  is  the  case  where  the 
combined  motor-generator  replaces  the  fly-wheel  in  an 
automobile  engine.  The  not  or  may  also  drive  the  engine 
by  means  of  a  silent  chain  or  by  direct  gear  reduction. 

Every  electric  starter  must  use  a  switch  of  some  kind 
for  starting  purposes  and  most  systems  include  an  out- 
put regulator  and  a  reverse  current  cut-out.  The  output 
regulator  is  a  simple  device  that  regulates  the  strength 
of  the  generator  current  that  is  supplied  the  storage  bat- 
tery. A  reverse  current  cut-out  is  a  form  of  check 
valve  that  prevents  the  storage  battery  from  discharging 
through  the  generator.  Brief  mention  is  made  of  electric 
starting  because  such  systems  will  undoubtedly  be  incor- 
porated in  some  future  airplane  designs.  Battery  igni- 
tion is  already  being  experimented  with. 

BATTERY   IGNITION    SYSTEM   PARTS 

A  battery  ignition  system  in  its  simplest  form  consists 
of  a  current  producer,  usually  a  set  of  dry  cells  or  a 
storage  battery,  an  induction  coil  to  transform  the  low 
tension  current  to  one  having  sufficient  strength  to  jump 


Battery  Ignition  System  Parts  571 

the  air  gap  at  the  spark-plug,  an  igniter  member  placed 
in  the  combustion  chamber  and  a  timer  or  mechanical 
switch  operated  by  the  engine  so  that  the  circuit  will  be 
closed  only  when  it  is  desired  to  have  a  spark  take  place 
in  the  cylinders.  Battery  ignition  systems  may  be  of  two 
forms,  those  in  which  the  battery  current  is  stepped  up 
or  intensified  to  enable  it  to  jump  an  air  gap  between  the 
points  of  the  spark  plug,  these  being  called  "high  ten- 
sion" systems  and  the  low  tension  form  (never  used  on 
airplane  motors)  in  which  the  battery  current  is  not  inten- 
sified to  a  great  degree  and  a  spark  produced  in  the  cylin- 
der by  the  action  of  a  mechanical  circuit  breaker  in  the 
combustion  chamber.  The  low  tension  system  is  the  sim- 
plest electrically  but  the  more  complex  mechanically. 
The  high  tension  system  has  the  fewest  moving  parts  but 
numerous  electrical  devices.  At  the  present  time  all  air- 
plane engines  use  high  tension  ignition  systems,  the  mag- 
neto being  the  most  popular  at  the  present  time.  The 
current  distribution  and  timing  devices  used  with  modern 
battery  systems  are  practically  the  same  as  similar  parts 
of  a  magneto. 


INDEX 


Action  of  Four-cycle  Engine 38 

Action  of  Le  Ehone  Kotary  Engine 503 

Action  of  Two-cycle  Engine 41 

Action  of  Vacuum  Feed  System   119 

Actual   Duration   of   Different   Functions    93 

Actual  Heat  Efficiency   62 

Adiabatic  Diagram   51 

Adiabatic  Law  . 50 

Adjustment  of  Bearings   449 

Adjustment    of    Carburetors 151 

Aerial  Motors,  Must  be  Light  20 

Aerial  Motors,  Operating  Conditions  of    19 

Aerial   Motors,   Requirements   of 19 

Aeromarine  Six-cylinder  Engine    527 

Aeronautics,  Division  in  Branches 18 

Aerostatics    18 

Air-cooled  Engine  Design 229 

Air-cooling  Advantages  231 

Air-cooling,  Direct  Method .'...: 228 

Air-cooling  Disadvantages 231 

Air-cooling  Systems    223- 

Aircraft,  Heavier  Than  Air '  17 

Aircraft,  Lighter  Than  Air 18 

Aircraft  Types,  Brief  Consideration  of 17 

Air  Needed  to  Burn  Gasoline 113 

Airplane  Engine,  Power  Needed 21 

Airplane  Engines,  Overhauling   412 

Airplane   Engine,   How  to  Time    269 

Airplane  Engine  Lubrication   209 

Airplane,  How  Supported   21 

Airplane  Motors,  German 543 

Airplane  Motor  Types 20 

Airplane  Motors,  Weight   of    * 21 

Airplane  Power  Plant  Installation 324 

Airplane  Types    18 

Airplanes,  Horse-power  Used  in 26 

Air  Pressure  Diminution,  With  Altitude 144 

Altitude,  How  it-  Affects  Mixture    153 

Aluminum,  Use  in  Pistons 297 

573 


574  Index 

PAGE 

American  Aviation  Engines,  Statistics   546 

Anzani  Badial  Engine  Installation   344 

Anzani  Six-cylinder  Star  Engine   465 

Anzani  Six-cylinder  Water-cooled  Engine    459 

Anzani  Ten-  and  Twenty-cylinder  Engines   468 

Anzani  Three-cylinder  Engine 459 

Anzani  Three-cylinder  Y  Type   462 

Argus  Engine  Construction 545 

Armature   Windings 168 

Atmospheric  Conditions,  Compensating  for 143 

Austro-Daimler  Engine    557 

Aviatics 18 

Aviation  Engine,  Aeromarine 527 

Aviation  Engine,  Anzani  Six-cylinder  Star 465 

Aviation  Engine,  Canton  and,  Unne   469 

Aviation  Engine   Cooling 219 

Aviation  Engine,  Curtiss 519 

Aviation  Engine  Cylinders 233 

Aviation  Engine,  Early  Gnome  472 

Aviation  Engine,   German   Gnome   Type    495 

Aviation  Engine,  Gnome  Monosoupape : 486 

Aviation  Engine,  How   To   Dismantle    415 

Aviation  Engine,  How  to  Start 460 

Aviation  Engine,  Le  Ehone  Rotary  495 

Aviation  Engine  Oiling   218 

Aviation  Engine  Parts,  Functions  of    ; 82 

Aviation  Engine,  Renault   Air-cooled    507 

Aviation  Engine,  Stand  for   Supporting    414 

Aviation  Engine,  Sturtevant 515 

Aviation  Engine,  Thomas-Morse 521 

Aviation  Engine  Types    457 

Aviation  Engine,  Wisconsin 531 

Aviation  Engines,  Anzani  Six-cylinder    Water-cooled 459 

Aviation  Engines,  Anzani  Ten-  and  Twenty-cylinder    468 

Aviation  Engines,  Anzani  Three-cylinder 459 

Aviation  Engines,  Anzani  Y  Type 462 

Aviation  Engines,  Argus 545 

Aviation  Engines,  Austro-Daimler    557 

Aviation  Engines,  Benz. 551 

Aviation  Engines,  Four-   and   Six-cylinder 88 

Aviation  Engines,     German 543 

Aviation  Engines,  Hall-Scott 539 

Aviation  Engines,  Hispana-Suiza    512 

Aviation  Engines,  Mercedes     543 

Aviation  Engines,  Overhauling  412 

Aviation  Engines,  Principal  Parts  of   80 

Aviation  Engines,  Starting  Systems  For   567 

Aviation  Engines,  Sunbeam     558 


Index  575 

B 

PAGE 

Balanced  Crank-shafts 318 

Ball-bearing   Crank-shaf fs   319 

Battery  Ignition  Systems   571 

Baverey   Compound   Nozzle    , 137 

Bearings,  Adjustment   of 449 

Bearing  Alignment 453 

Bearing  Brasses,  Fitting 450 

Bearing  Parallelism,  Testing   453 

Bearing  Scrapers  and  Their  Use 446 

Benz  Aviation  Engines 551 

Benz  Engine  Statistics 551 

Berling  Magneto ...*!" 174 

Berling  Magneto,  Adjustment  of   180 

Berling  Magneto    Care 180 

Berling  Magneto  Circuits 176 

Berling  Magneto,  Setting   178 

Block    Castings 234 

Blowing   Back 269 

Bolts,  Screwing  Down   452 

Bore  and  Stroke  Eatio 240 

Boyles  Law 49 

Brayton  Engine 48 

Breaker  Box,  Adjustment  of 180 

Breast  and  Hand  Drills  387 

Burning  Out  Carbon  Deposits   421 

Bushings,  Camshaft,  Wear  in 456 


c 

Calipers,  Inside  and  Outside   398 

Cam  Followers,  Types  of   260 

Cams  for  Valve  Actuation 259 

Cam-shaft  Bushings 456 

Cam-shaft  Design 313 

Cam-shaft  Drive   Methods    .' 261 

Cam-shaft    Testing    451 

Cam-shafts   and  Timing  Gears 456 

Canton  and  Unne  Engine   469 

Carbon,  Burning  out  with  Oxygen   421 

Carbon  Deposits,  Cause  of   418 

Carbon  Eemoval    419 

Carbon  Scrapers,  How  Used    420 

Carburetion  Principles 112 

Carburetion  System  Troubles 355 

Carburetor,    Claudel    ..." 127 

Carburetor,  Compound  Nozzle  Zenith   135 


576  Index 

PAGB 

Carburetor,  Concentric  Float  and  Jet  Type   125 

Carburetor,  Duplex  Zenith 138 

Carburetor,  Duplex  Zenith,  Trouble  in   357 

Carburetor  Installation,  In  Airplanes    148 

Carburetor,  Le   Rhone , 501 

Carburetor,  Master  Multiple  Jet  , 133 

Carburetor,  Schebler     125 

Carburetor  Troubles,  How  to  Locate  354 

Carburetor,  Two  Stage  131 

Carburetor,  What  it  Should  Do 114 

Carburetors,  Float  Feed    .  ^ 122 

Carburetors,  Multiple  Nozzle  130 

Carburetors,  No*es  on  Adjustment 151 

Carburetors,  Reversing  Position  of 149 

Carburetors,  Spraying    120 

Care  of  Dixie  Magneto   188 

Castor  Oil,  for  Cylinder  Lubrication  205 

Castor  Oil,  Why  Used  In  Gnome  Engines 211 

Center  Gauge   403 

Chisels,  Forms  of   384 

Christensen  Air  Starting  System 567 

Circuits,    Magnetic    161 

Classification   of   Engines    458 

Claudel  Carburetor 127 

Cleaning   Distributor 180 

Clearances  Between  Valve  Stem  and  Actuators  261 

Combustion  Chamber  Design   239 

Combustion  Chambers,  Spherical 76 

Common  Tools,  Outfit  of  378 

Comparing  Two-cycle  and  Four-cycle  Types   44 

Compound  Cam  Followers  260 

Compound  Piston  Rings.   301 

Compressed  Air  Starting  System 565 

Compression,  Factors  Limiting   69 

Compression,  in  Explosive  Motors,  Value  of   68 

Compression  Pressures,  Chart  for    72 

Compression    Temperature    71 

Computations  for  Horse-power  Needed   25 

Computations  for  Temperature 52 

Concentric   Piston   Ring 299 

Concentric    Valves 255 

Connecting  Rod  Alignment,  Testing   454 

Connecting  Rod,   Conventional 308 

Connecting  Rod  Forms 305 

Connecting  Rod,  Gnome  Engine    305 

Connecting  Rods,  Fitting    449 

Connecting  Rods  for  Vee  Engines 310 

Connecting  Rods,  Le  Rhone 498 


Index  577 

PAGE 

Connecting  Rods,  Master    310 

Constant  Level  Splash  System 215 

Construction  of  Dixie  Magneto '. 186 

Construction  of  Pistons 288 

Conversion  of  Heat  to  Power  '...., 58 

Cooling  by  Air    223 

Cooling  by  Positive  Water  Circulation   224 

Cooling,  Heat  Loss  in   66 

Cooling  System   Defects 358 

Cooling  Systems  Used    223 

Cooling  Systems,  Why  Needed 219 

Cotter  Pin  Pliers 384 

Crank-case,    Conventional    320 

Crank-case  Forms    320 

Crank-case,  Gnome    323 

Crank-shaft,  Built  Up 315 

Crank-shaft  Construction     315 

Crank-shaft  Design     315 

Crank-shaft  Equalizer    449 

Crank-shaft  Form 315 

Crank-shaft,  Gnome  Engine : 483 

Crank-shafts,  Balanced 318 

Crank-shafts,  Ball  Bearing 319 

Cross  Level 403 

Crude  Petroleum,  Distillates  of    Ill 

Curtiss  Aviation  Engines    519 

Curtiss  Engine  Installation    328 

Curtiss  Engine  Repairing  Tools    408 

Cutting  Oil  Grooves   448 

Cylinder  Blocks,   Advantages   of    237 

Cylinder  Block,  Duesenberg 235 

Cylinder  Castings,  Individual 234 

Cylinder  Construction    233 

Cylinder  Faults   and   Correction    416 

Cylinder  Form  and  Crank-shaft  Design    238 

Cylinder  Head    Packings 417 

Cylinder  Head,  Eemovable   239 

Cylinder,   I  Head  Form 248 

Cylinder,  L  Head  Form 248 

Cylinder  Oils 206 

Cylinder  Placing 20 

Cylinder  Placing   in   V   Motor 99 

Cylinder  Retention,  Gnome    475 

Cylinder,  T  Head  Form 248 

Cylinders,  Cast  in  Blocks  235 

Cylinders,  Odd  Number  in  Rotary  Engines  482 

Cylinders,  Repairing  Scored 423 

Cylinders,  Valve  Location  in    ; 245 


578  Index 

D 

PAGE 

Defects  in  Cylinders    417 

Defects  in  Dry   Battery 373 

Defects  in  Fuel  System    354 

Defects  in  Induction    Coil 373 

Defects  in  Magneto    372 

Defects  in  Storage  Battery   372 

Defects  in  Timer ! 373 

Defects  in  Wiring  and  Eemedies   . . . 373 

Die  Holder   , 394 

Dies  for  Thread  Cutting , 395 

Diesel  Motor  Cards    67 

Diesel  System 144 

Direct  Air  Cooling   228 

Dirigible  Balloons  18 

Dismantling  Airplane  Engine 415 

Distillates  of  Crude  Petroleum Ill 

Division  of  Circle  in  Degrees 268 

Dixie  Ignition   Magneto    184 

Dixie  Magneto,  Care  of 188 

Draining  Oil  From  Crank-case 214 

Drilling  Machines   386 

Drills,  Types  and  Use 388 

Driving  Cam-shaft,  Methods  of 262 

Dry  Cell  Battery,  Defects  in  373 

Duesenberg  Sixteen  Valve  Engine 525 

Duesenberg  Valve  Action 255 

Duplex  Zenith  Carburetor   138 

E 

Early  Gnome  Motor,  Construction  of 472 

Early  Ignition  Systems   155 

Early  Types  of  Gas  Engine • 28 

Early  Vaporizer  Forms  120 

Eccentric  Piston  Eing   299 

Economy,  Factors  Governing 64 

Efficiency,  Actual   Heat 62 

Efficiency,  Maximum  Theoretical   61 

Efficiency,  Mechanical    .' • 62 

Efficiency  of  Internal  Combustion  Engine   60 

Efficiency,  Various  Measures  of   61 

Eight-cylinder  Engine   95 

Eight-cylinder  Timing  Diagram    , 276 

Electricity  and  Magnetism,  Relation  of   162 

Electrical  Ignition  Best 156 

Electric  Starting  Systems    569 

Engine,  Advantages  of  V  Type • 95 


Index  579 


Engine  Base  Construction 319 

Engine  Bearings,  Adjusting 443 

Engine  Bearings,  Refitting 442 

Engine  Bed  Timbers,  Standard  330 

Engine,  Four-cycle,  Action  of  .' .- 38 

Engine,  Four-cycle,  Piston  Movements  in   40 

Engine  Functions,  Duration  of : 93 

Engine  Ignition,  Locating  Troubles    353 

Engine  Installation,  Gnome    . . . . . 344 

Engine  Installation,   Anzani   Radial    t 344 

Engine  Installation,    Hall-Scott 332 

Engine  Installation,  Rotary  342 

Engine  Operation,   Sequence  of 84 

Engine  Parts  and  Functions 80 

Engine  Starts  Hard,  Ignition  Troubles  Causing 369 

Engine  Stoppage,  Causes  of 347 

Engine  Temperatures 221 

Engine  Trouble   Charts    369 

Engine  Troubles,  Cooling 358 

Engine  Troubles,  Hints  For  Locating : 345 

Engine  Troubles,  Ignition 353 

Engine  Troubles,  Noisy  Operation  359 

Engine  Troubles,   Oiling    357 

Engine  Troubles  Summarized 350 

Engine,  Two-cycle,  Action  of    41 

Engines,   Classification  of 458 

Engines,  Cylinder  Arrangement 31-32 

Engines,  Eight-cylinder  V 95 

Engines,  Four-cylinder  Forms 88 

Engines,  Graphic  Comparison  of   33-34-35 

Engines,  Internal  Combustion,  Types  of 30 

Engines,  Multiple  Cylinder,  Power  Delivery  in 91 

Engines,  Multiple   Cylinder,  Why  Best    .....' 83 

Engines,  Rotary  Cylinder  107 

Engines,  Six-cylinder  Forms 88 

.Engines,  Twelve-cylinder    96 

Equalizer,  Crank-shaft 449 

Exhaust  Closing    270 

Exhaust  Valve  Design,  Early  Gnome    475 

Exhaust  Valve  Opening 270 

Explosive  Gases,  Mixtures  of   56 

Explosive  Motors,  Inefficiency  in   74 

Explosive  Motors,  Why  Best    27 

F 

Factors  Governing  Economy    64 

Eactors  Limiting   Compression '. .  70 

Faults  in   Ignition    352 


580  Index 

PAGE 

Figuring  Horse-power  Needed 21 

Files,  Use  and  Care  of  383 

First  Law  of  Gases 49 

Fitting  Bearings  By  Scraping    447 

Fitting  Brasses    '. . . . . 450 

Fitting  Connecting  Eods 449 

Fitting  Main   Bearings 448 

Fitting  Piston  Eings    439 

Float  Feed  Carburetor  Development   124 

Float  Feed  Carburetors 122 

Force  Feed  Oiling  System 218 

Forked  Connecting  Eods 310 

Four-cycle  Engine,  Action  of ' 38 

Four-cycle  Engine,  Why  Best    45 

Fourteen-cylinder  Engine    474 

Four  Valves  Per  Cylinder 284 

Friction,  Definition  of . 302 

Fuel  Feed  By  Gravity  116 

Fuel  Feed  by  Vacuum  Tank   117 

Fuel  Storage  and  Supply    116 

Fuel  Strainers,  Types  of 141 

Fuel  Strainers,   Utility   of    140 

Fuel .  System  Faults    354 

Fuel  System  Installation,  Hall-Scott  336 

Fuel  System,   Gnome 490 

Fuel  Utilization  Chart  .  62 


G 

Gas  Engine,  Beau  de  Eocha  'a  Principles   59 

Gas  Engine  Development 28 

Gas  Engine,  Early  Forms  of 48 

Gas  Engine,  Inventors  of  29 

Gas  Engine,  Theory  of   47 

Gases,   Compression   of t * 49 

Gases,  First  Law  of   ^ 49 

Gases,  Second  Law  of •  50 

Gaskets,  How  to  Use 452 

Gasoline,  Air  Needed  to  Burn   113 

Gas  Engines,  Parts  of  80 

Gas  Vacuum  Engine,  Brown 's    28 

German  Airplane  Motors 543 

German  Gnome  Type  Engine 495 

Gnome  Aviation  Engine,  Early  Form   472 

Gnome  Crank-shaft  483 

Gnome   Cylinder,   Machining    489 

Gnome  Cylinder   Eetention    475 

Gnome  Engine,  Fuel^  Lubrication  and  Ignition 490 


Index  581 


Gnome  Engine,  German  Type   495 

Gnome  Engine  Installation 344 

Gnome  Firing  Order  . . .  * 482 

Gnome  Fourteen-Cylinder  Engine .' .  474 

Gnome  Fourteen-cylinder  Engine  Details 480 

Gnome   Monosoupape,  How  to  Time 278 

Gnome  Monosoupape  Type  Engine  486 

Graphic  Comparison  of  Engine  Types 33-34-35 

Graphic  Comparison,  Two-  and  Four-cycle 46 

Gravity  Feed  System '. 116 

Grinding  Valves 429 


H 

Hall-Scott  Aviation  Engines 539 

Hall-Scott  Engine   Installation 332 

Hall-Scott  Engine,  Preparations  For  Starting   '341 

Hall-Scott  Engine-   Tools 410 

Hall-Scott  Lubrication  System    211 

Hall-Scott  Statistic  Sheet 544 

Heat  and  Its  Work 54 

Heat  in   Gas  Engine   Cylinder 69 

Heat  Given  to   Cooling  Water    78 

Heat  Loss,   Causes   of    74 

Heat  Loss  in  Airplane'  Engine   221 

Heat  Loss  in  Wall  Cooling   65 

High  Altitude,  How  it  Affects  Power    144 

High  Tension  Magneto 172 

Hints  For  Locating  Engine  Troubles 345 

Hints  for  Starting  Engine 361 

Hispana-Suiza  Model  A  Engine 512 

Horse-power  Needed  in  Airplane   21 

Horse-power  Needed,  How  Figured    22 

How  An  Engine  is  Timed : 277 


I 

Ignition,  Electric 156 

Ignition,   Elements  of 157 

Ignition    of    Gnome    Engine    490 

Ignition  System,  Battery    571 

Ignition  Systems,   Early    155 

Ignition  System    Faults 352 

Ignition,  Time   of 273 

Ignition,  Two  Spark 196 

I  Head  Cylinders -. 248 

Improvements   in   Gas   Engines    29 

Indicating  Meters,  Engine    Speed 563 


582  Index 

PAGE 

Indicating  Meters,  Oil  and  Air  Pressure  563 

Indicator  Cards,  How  To  Eead    66 

Indicator  Cards,  Value   of    • 66 

Individual   Cylinder   Castings 234 

Induction    Coil,   Defects   in 373 

Inefficiency,  Causes  of 74 

Inlet  Valve  Closing ' 272 

Inlet  Valve  Opening 270 

Installation,  Airplane  Engine    324 

Installation,  Curtiss    OX    2    Engine    328 

Installation,  Hall-Scott  Engine 332 

Installation  of  Eotary  Engines 342 

Intake   Manifold   Construction    143 

Intake  Manifold  Design    142 

Internal  Combustion  Engine,  Efficiency  of    60,  62 

Internal  Combustion  Engines,  Main  Types  of 30 

Inverted  Engine   Placing    -. 325 

Isothermal  Diagram    51 

Isothermal  Law   .  48 


K 

Keeping  Oil  Out  of  Combustion  Chamber 303 

Knight  Sleeve  Valves ..266 


L 

Lag  and  Lead,  Explanation  of 268 

Lapping  Crank-pins 445 

Lead  Given  Exhaust  Valve 270 

Leak  Proof  Piston  Eings  ...... *  301 

Lenoir  Engine  Action 48 

Le  Ehone  Cams  and  Valve  Actuation 500 

Le  Ehone  Carburetor 501 

Le  Ehone  Connecting  Eod  Assembly,  Distinctive , 498 

Le  Ehone  Engine  Action 503 

Le  Ehone  Eotary  Engine 495 

L  Head  Cylinders   248 

Liquid  Fuels,   Properties   of    110 

Locating  Carburetor    Troubles 354 

Locating  Engine   Troubles 350 

Locating  Ignition  Troubles    .. .  .  .^  .  353 

Locating  Oiling   Troubles    357 

Location  of  Magneto  Trouble   181 

Losses   in   Wall   Cooling    65 

Lost  Power  and  Overheating,  Summary  of  Troubles  Causing 363 

Lubricants,  Derivation    of    204 

Lubricants,  Eequirements  of   204 


Index  588 

PAGE 

Lubricating  System   Classification    208 

Lubricating  Systems,   Selection   of    • .' 208 

Lubrication  By  Constant  Level  Splash  System   215 

Lubrication  By  Dry    Crank-case    Method    218 

Lubrication  By  Force  Feed   Best    218 

Lubrication  of  Magneto    180 

Lubrication  System,    Gnome    490 

Lubrication  System,    Hall-Scott 211 

Lubrication  System,  Thomas-Morse    '. .  210 

Lubrication,  Theory  of 202 

Lubrication,  Why  Necessary 201 


M 

Magnetic  Circuits 161 

Magnetic  Influence  Defined   158 

Magnetic  Lines  of  Force 161 

Magnetic  Substances 158 

Magnetism,  Flow  Through  Armature   166 

Magnetism,  Fundamentals   of    157 

Magnetism,  Eelation  to  Electricity   162 

Magneto,  Action  of  High  Tension   173 

Magneto  Armature  Windings 168 

Magneto,  Basic    Principles    of    163 

Magneto"   Berling 174 

Magneto,  Defects  in .-.   372 

Magneto  Distributor,  Cleaning 180 

Magneto  Ignition  Systems    169 

Magneto  Ignition  Wiring     179 

Magneto  Interrupter,  Adjustment   of    180 

Magneto,  Low   Voltage 168 

Magneto,  Lubrication   of 180 

Magneto  Maintenance    180 

Magneto,  Method  of  Driving 175 

Magneto  Parts*  and  Functions  167 

Magneto,  The  Dixie 184 

Magneto  Timing '. 179 

Magneto,  Timing   Dixie 188 

Magneto,  Transformer  System    .. . . 171 

Magneto    Trouble,   Location    of    181 

Magneto,  True   High    Tension    172 

Magneto,  Two   Spark  Dual 177 

Magnets,  Forms  of   ' 160 

Magnets,  How  Produced 162 

Magnets,  Properties  of 159 

Main  Bearings,  Fitting 448 

Manifold,    Intake 143 

Master  Multiple  Jet  Carburetor  ." .  133 


584  Index 

PAGE 

Master  Rod  Construction    310 

Maximum  Theoretical   Efficiency    61 

Meaning  of  Piston  Speed 241 

Measures  of  Efficiency 61 

Measuring  Tools 397 

Mechanical   Efficiency    \ 62 

Mercedes   Aviation   Engine    543 

Metering  Pin   Carburetor,   Stewart    128 

Micrometer   Caliper,   Eeading    405 

Micrometer  Calipers,  Types  and  Use 404 

Mixture,  Effect  of  Altitude  on 153 

Mixture,  Proportions  of 151 

Mixture,  Starvation  of 149 

Monosoupape  Gnome  Engine   486 

Mother  Eod,  Gnome  Engine    305 

Motor  Misfires,  Carburetor  Faults   Causing    374 

Motor  Misfires,  Ignition  Troubles  Causing    370  ' 

Motor  Eaces,  Carburetor  Faults  Causing 374  1 

Motor  Starts  Hard,  Carburetor  Faults  Causing  -.- 374 ' 

Motor  Stops  In  Flight,  Carburetor  Faults  374 

Motor  Stops  Without  Warning,  Ignition  Troubles 370 

Multiple  Cylinder  Engine,  Why  Best    83 

Multiple  Nozzle  Vaporizers    129 

Multiple  Valve  Advantages  286 

N 

Noisy  Engine  Operation,  Causes  of 359 

Noisy  Operation,  Carburetor  Faults  Causing  374 

Noisy  Operation,  Summary  of  Troubles  Causing 365 

O 

Off-set  Cylinders,  Eeason  for  243 

Oil  Bi-pass,  Function  of 213  * 

Oil,  Draining  From  Crank-case   214 

Oil  Grooves,   Cutting 448 

Oil  Pressure  in  Hall-Scott  System 214 

Oil  Pressure  Eelief  Bi-pass 213 

Oiling  System   Defects    . >§57 

Oils  for  Cylinder  Lubrication 206 

Oils  for  Hall-Scott  Engine   215 

Oils  for  Lubrication 204 

Operating  Principles  of  Engines 37 

Oscillating  Pist.on  Pin   295 

Otto  Four-cycle  Cards   67 

Overhauling   Aviation    Engines    412 

Overhead  Cam-shaft  Location 252 

Overheating,  Causes  of 359 


Index  585 

p 

PAGE 

Panhard    Concentric    Valves 255 

Petroleum,  Distillates  of Ill 

Piston,    Differential    291 

Piston  Pin    Eetention    293 

Piston  Ring  Construction   298 

Piston  Eing    Joints     ' 299 

Piston  Eing  Manipulation    438 

Piston  Eing  Troubles     437 

Piston  Rings,    Compound 301 

Piston  Eings,    Concentric    299 

Piston  Eings,  Eccentric , .  299 

Piston  Eings,  Fitting 439 

Piston  Eings,  Leak  Proof 301 

Piston  Eings,  Eeplacing    441 

Piston  Speed  in  Airplane   Engines    241 

Piston  Speed,  Meaning  of .' ..: 241 

Piston  Troubles    and   Eemedies    436 

Pistons,   Aluminum 296 

Pistons,  Details  of   288 

Pistons  for  Two-cycle  Engines 289 

Positive   Valve   Systems    283 

Power,  Affected  by  High  Altitude 145 

Power  Delivery  in  Multiple  Cylinder  Engines 91 

Power,  How  Obtained  From  Heat ' 58 

Power  Needed  in  Airplane  Engines 21 

Power  Used  in  Airplanes   26* 

Precautions  in  Assembling  Parts   452 

Pressure  Belief  Fitting 213 

Pressures  and  Temperatures 63 

Principles   of    Carburetion 112 

Principles  of  Magneto  Action  163 

Properties  of  Cylinder  Oils 207 

Properties  of  Liquid  Fuels 110 

Pump  Circulation  Systems   226 

Pump  Forms /....'. 226 

B 

Eadial  Cylinder  Arrangement   . 103 

Eeading  Indicator  Cards   67 

Eeamers,  Types  and  Use 392 

Eeassembling  Parts,  Precautions  in   451 

Eemovable  Cylinder  Head 239 

Renault  Air  Coded  Engine 507 

Renault  Engine  Details 508 

Repairing  Scored  Cylinders    423 

Requisites  for  Best  Power  Effect   59 


586  Index 

PAGE 

Reseating  and  Truing  Valves   426 

Resistance,  Influence  of 22 

Rotary  Cylinder   Engines 107 

Rotary  Engine,    Le    Rhone    495 

Rotary  Engines,  Castor  Oil  for  211 

Rotary  Engines,  Installing  342 

Rotary  Engines,  Why  Odd  Number  of  Cylinders   109 

Rotary  Engines,  Why  Odd  Number  of  Cylinders  Is  Used 482 


S 

S.  A.  E.  Engine  Bed  Dimensions 330 

Salmson   Nine-cylinder  Engine    470 

Scissors  Joint   Rods    310 

Scored    Cylinders,   Repairing    '. 422 

Scrapers,  Types  of  Bearing  446 

Scraping  Bearings  to  Fit   . .- 447 

Second  Law  of  Gases    50 

Sequence   of   Engine   Operation    84 

Shebler    Carburetor 125 

Six-cylinder  Timing  Diagram    275 

Sixteen  Valve  Duesenberg  Engine 525 

Skipping  or  Irregular  Operation,  Causes  of   367 

Sliding  Sleeve  Valves 266 

Spark  Plug  Air  Gaps,  Setting ; 197 

Spark  Plug,  Design  of  193 

Spark  Plug,  Mica 194 

Spark  Plug,  Porcelain    193 

Spark  Plugs,  Defects  in    371 

Spark  Plugs  for  Two  Spark  Ignition : 197 

Spark  Plug,  Special  for  Airplane  Engine 199 

Spark  Plug,  Standard  S.  A.  E.    . 195 

Spherical   Combustion    Chambers 76 

Splash  Lubrication    215 

Split  Pin  Remover 384 

Spraying    Carburetors 120 

Springiest   Valves 280 

Springs,   for  Valves 263 

Spring  Winder   . 384 

Sprung   Cam-shaft,   Testing    451 

Stand  for  Supporting  Engine 414 

Starting  Engine,  Hints  for 361 

Starting  Hall-Scott  Engine 341 

Starting  System,   Christensen 567 

Starting  Systems,  Compressed  Air  . -. 565 

Starting  Systems,  Electric 569 

Statistics,  American  Engines    ' 546,  547 

Statistic  Sheet,  Hall-Scott  Engines   544 


Index  587 


Statistics  of  Benz  Engine 551 

Steam  Engine,  Efficiency  of    59 

Steam  Engine,  Why  Not  Used 27 

Steel  Scale,  Machinists ' 399 

Stewart   Metering  Pin   Carburetor    128 

Storage  Battery,  Defects  in    372 

Stroke  and  Bore  Eatio 240 

Sturtevant  Model  5A  Engine    515 

Summary  of  Engine  Types 30 

Sunbeam  Aviation  Engines    : 588 

Sunbeam  Eighteen-Cylinder  Engine   561 


T 

Tap  and  Die  Sets 397 

Taps  for  Thread  Cutting   , 394 

Tee  Head  Cylinders 247 

Temperature  Computations * 52 

Temperatures  and  Explosive  Pressures 64 

Temperatures   and  Pressures    63 

Temperatures,  Operating '.'.'.". ; . . 221 

Testing  Bearing  Parallelism 453 

Testing  Connecting  Eod   Alignment    454 

Testing  Fit  of  Bearings 446 

Testing  Sprung  Cam-shaft ' 451 

Theory  of  Gas  Engine 47 

Theory  of  Lubrication 203 

Thermo-syphon  Cooling  System  227 

Thomas-Morse  Aviation  Engine    521 

Thomas-Morse  Lubrication  System 210 

Thread  Pitch  Gauge   403 

Time  of  Ignition  273 

Timer,  Defects  in  373 

Times  of  Explosion 56 

Timing  Dixie  Magneto 188 

Timing  Gears,  Effects  of  Wear 456 

Timing  Magneto    179 

Timing  Valves 267 

Tool  Outfits,  Typical 408 

Tools  for  Adjusting  and  Erecting   '. 378 

Tools  for  Bearing  Work 445 

Tools  for  Curtiss  -Engines 408 

Tools  for  Grinding  Valves 430 

Tools  for  Hall-Scott  Engines   410,  411 

Tools  for  Measuring 397 

Tools  for  Eeseating  Valves * 426 

Trouble  in  Carburetion  System 355 

Trouble,  Location  of  Magneto 181 


588  Index 

PAGE 

Troubles,  Engine,  How  to  Locate 345 

Troubles,  Ignition   353 

Troubles  in  Oiling  System   357 

True  High  Tension  Magneto 172 

Twelve-Cylinder  Engines 96 

Two-  and  Four-Cycle  Types,  Comparison  of    44 

Two-Cycle  Engine    Action    41 

Two-Cycle  Three-Port  Engine    43 

Two-Cycle  Two-Port  Engine  42 

Two-Spark  Ignition 196 

Two-Stage  Carburetor 131 

Types  of  Aircraft   17 

Types  of  Internal  Combustion  Engines 30 


V 

Vacuum  Fuel  Feed,  Stewart 119 

Value  of  Compression    69 

Value  of  Indicator  Cards 66 

Valve  Actuation,  Le  Rhone   500 

Valve  Design  and  Construction  256 

Valve-Grinding  Processes 429 

Valve-Lifting  Cams    259 

Valve-Lifting  ^lungers 260 

Valve  Location  Practice   245 

Valve  Operating  Means 252 

Valve  Operating  System,  Depreciation  in 433 

Valve   Operation 258 

Valve  Eemoval  and  Inspection 424 

Valve  Seating,  How  to  Test   432 

Valve  Springs  263 

Valve  Timing,  Exhaust   270 

Valve  Timing,  Gnome  Monosoupape * 278 

Valve  Timing,  Intake 270 

Valve  Timing,  Lag  and  Lead 269 

Valve  Timing  Proceedure 277 

Valve   Timing  Practice 267 

Valves,  Electric  Welded 258 

Valves,  Flat  and  Bevel  Seat 257 

Valves,  Four  per  Cylinder 284 

Valves,  How  Placed  in  Cylinder 247 

Valves  in  Cages   249 

Valves  in  Removable  Heads   249 

Valves,  Materials  Used  for 258 

Valves,  Reseating   . .  .. 426 

Vaporizer,  Simple  Forms  of    120 

V  Engines,  Cylinder  Arrangement  in 102 

Vernier,  How  Used .401 


Index  589 

w 

PAGE 

Wall  Cooling,  Losses  in 65 

Water  Cooling  by  Natural  Circulation   227 

Water   Cooling   System    , 224 

Weight  of  Airplane  Motors 21 

Wiring,  Defects  in 373 

Wiring  Magneto  Ignition  System  179 

Wisconsin  Engines    531 

Wrenches,  Forms  of   380 

Wristpin  Retention   293 

Wristpin  Retention  Locks 295 

Wristpin  Wear  and  Remedy   442 


Z 

Zenith  Carburetor,  Action  of 137 

Zenith  Duplex  Carburetor,  Troubles  in 356 

Zenith  Carburetor  Installalion 139 


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INDEX 


PAGES 

Air  Brakes 21,  24 

Arithmetic 14,  25,  31 

Automobile  Books 3,  4,  5,  6 

Automobile  Charts 6,  7 

Automobile  Ignition  Systems 5 

Automobile  Lighting 5 

Automobile  Questions  and  Answers 4 

Automobile  Repairing 4 

Automobile  Starting  Systems 5 

Automobile  Trouble  Charts 5,  6 

Automobile  Welding 5 

Aviation 7 

Aviation  Chart. 7 

Batteries,  Storage 5 

Bevel  Gear 19 

Boiler-Room  Chart 9 

Brazing 7 

Cams 19 

Carburetion  Trouble  Chart 6 

Change  Gear -. 19 

Charts 6,  7,  8 

Coal 22 

Coke 9 

Combustion 22 

Compressed  Air 10 

Concrete 10,  11,  12 

Concrete  for  Farm  Use 11 

Concrete  for  Shop  Use. 11 

Cosmetics 27 

Cyclecars 5 

Dictionary 12 

Dies 12,13 

Drawing 13,  14 

Drawing  for  Plumbers 28 

Drop  Forging. 13 

Dynamo  Building 14 

Electric  Bells 14 

Electric  Switchboards 14,  16 

Electric  Toy  Making 15 

Electric  Wiring .' 14,  15,  16 

Electricity 14,  15,  16,  17 

Encyclopedia 24 

E-T  Air  Brake 24 

Every-day  Engineering 34 

Factory  Management 17 

Ford  Automobile 3 

Ford  Trouble  Chart 6 

Formulas  and  Recipes , 29 

Fuel 17 

Gas  Construction 18 

Gas  Engines 18,  19 

Gas  Tractor 33 

Gearing  and  Cams 19 

Glossary  of  Aviation  Terms 7,12 

Heating : 31,  32 

Horse-Power  Chart. 9 

Hot-Water  Heating ,  .31,  32 

House  Wiring 15,  17 

How  to  Run  an  Automobile 3 

Hydraulics 5 

Ice  and  Refrigeration 20 

Ignition  Systems 5 

Ignition-Trouble  Chart 6 

India  Rubber 30 

Interchangeable  Manufacturing 24 

Inventions 20 

Knots 20 

Lathe  Work...  , .   20 


PAGES 

Link  Motions 22 

Liquid  Air 21 

Locomotive  Boilers 22 

Locomotive  Breakdowns 22 

Locomotive  Engineering 21,  22,  23,  24 

Machinist  Book 24,  25,  26 

Magazine,  Mechanical 34 

Manual  Training 26 

Marine  Engineering 26 

Marine  Gasoline  Engines 19 

Mechanical  Drawing 13,  14 

Mechanical  Magazine 34 

Mechanical  Movements 25 

Metal  Work 12,  13 

Motorcycles 5,  6 

Patents 20 

Pattern  Making 27 

Perfumery 27 

Perspective 13 

Plumbing 28,  29 

Producer  Gas 19 

Punches 13 

Questions  and  Answers  on  Automobile 4 

Questions  on  Heating 32 

Railroad  Accidents 23 

Railroad  Charts 9 

Recipe  Book 29 

Refrigeration 20 

Repairing  Automobiles 4 

Rope  Work 20 

Rubber 30 

Rubber  Stamps 30 

Saw  Filing 30 

Saws,  Management  of . . ., 30 

Sheet-Metal  Works 12,  13 

Shop  Construction 25 

Shop  Management 25 

Shop  Practice 25 

Shop  Tools 25 

Sketching  Paper t 14 

Soldering 7 

Splices  and  Rope  Work 20 

Steam  Engineering 30,  31 

Steam  Heating 31,  32 

Steel 32 

Storage  Batteries -5 

Submarine  Chart 9 

Switchboards 14,  16 

Tapers 21 

Telegraphy,  Wireless 17 

Telephone 16 

Thread  Cutting 26 

Tool  Making 24 

Toy  Making • 15 

Train  Rules 23 

Tractive  Power  Chart 9 

Tractor,  Gas 33 

Turbines 33 

Vacuum  Heating. 32 

Valve  Setting 22 

Ventilation ' 31 

Watch  Making 33 

Waterproofing 12 

Welding  with  Oxy-acetylene  Flame 5,  33 

Wireless  Telegraphy :  .    17 

Wiring... 14,  15 

Wiring  Diagrams 14 


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tion, 1918  Edition.     By  VICTOR  W.  PAGE,  M.S.A.E. 

This  is  the  most  complete,  practical  and  up-to-date  treatise  on  gasoline  automobiles  and  their 
component  parts  ever  published.  In  the  new  revised  and  enlarged  1918  edition,  all  phases  of 
automobile  construction,  operation  and  maintenance  are  fully  and  completely  described,  and 
in  language  anyone  can  understand.  Every  part  of  all  types  of  automobiles,  from  light  cycle- 
cars  to  heavy  motor  trucks  and  tractors,  are  described  in  a  thorough  manner,  not  only 
the  automobile,  but  every  item  of  it;  equipment,  accessories,  tools  needed,  supplies  and  spare 
parts  necessary  for  its  upkeep,  are  fully  discussed. 

It  is  dearly  and  concisely  written  by  an  expert  familiar  with  every  branch  of  the  automobile  industry 
and  the  originator  of  the  practical  system  of  self-education  on  technical  subjects.  It  is  a  liberal  edu- 
cation in  the  automobile  art,  useful  to  all  who  motor  for  either  business  or  pleasure. 
Anyone  reading  the  incomparable  treatise  is  in  touch  with  all  improvements  that  have  been 
made  in  motor-car  construction.  All  latest  developments,  such  as  high  speed  aluminum  motors 
and  multiple  valve  and  sleeve-valve  engines,  are  considered  in  detail.  The  latest  ignition, 
carburetor  and  lubrication  practice  is  outlined.  New  forms  of  change  speed  gears,  and  final 
power  transmission  systems,  and  all  latest  chassis  improvements  are  shown  and  described. 
This  book  is  used  in  all  leading  automobile  schools  and  is  conceded  to  be  the  STANDARD 
TREATISE.  The  chapter  on  Starting  and  Lighting  Systems  has  been  greatly  enlarged,  and 
many  automobile  engineering  features  that  have  long  puzzled  laymen  are  explained  so  clearly 
that  the  underlying  principles  can  be  understood  by  anyone.  This  book  was  first  published 
six  years  ago  and  so  much  new  matter  has  been  added  that  it  is  nearly  twice  its  original  size. 
The  only  treatise  covering  various  forms  of  war  automobiles  and  recent  developments  in  motor- 
truck design  as  well  as  pleasure  cars.  This  book  is  not  too  technical  for  the  layman  nor  too  elementary 
for  the  more  expert.  It  is  an  incomparable  work  of  reference  for  home  or  school.  1,000  6x9  pages, 
nearly  1,000  illustrations,  12  folding  plates.  Cloth  bound.  Price , .  .  .  .$3.00 

WHAT  IS  SAID  OF- THIS  BOOK: 

"  It  is  the  best  book  on  the  Automobile  seen  up  to  date." — J.  H.  Pile,  Associate  Editor  Auto- 
mobile Trade  Journal. 

"Every  Automobile  Owner  has  use  for  a  book  of  this  character." — The  Tradesman. 
"This  book  is  superior  to  any  treatise  heretofore  .published  on  the  subject." — The  Inventive  Age. 
"  We  know  of  no  other  volume  that  is  so  complete  in  all  its  departments,  and  in  which  the  wide 
field  of  automobile  construction  with  its  mechanical  intricacies  is  so  plainly  handled,  both  in 
the  text  and  in  the  matter  of  illustrations." — The  Motorist. 

"The  book  is  very  thorough,  a  careful  examination  failing  to  disclose  any  point  in  connection 
with  the  automobile,  its  care  and  repair,  to  have  been  overlooked." — Iron  Age. 
"Mr.  Page  has  done  a  great  work,  and  benefit  to  the  Automobile  Field." — W.  C.  Hasford, 
Mgr.  Y.  M.  C.  A-.  Automobile  School,  Boston,  Mass. 

"It  is  just  the  kind  of  a  book  a  motorist  needs  if  he  wants  to  understand  his  car." — American 
Thresherman. 


The  Model  T  Ford  Car,  Its  Construction,  Operation  and  Repair.    By  VICTOR 
W.  PAGE,  M.S.A.E. 

This  is  a  complete  instruction  book.  All  parts  of  the  Ford  Model  T  Car  are  described  and 
illustrated;  the  construction  is  fully  described  and  operating  principles  made  clear  to  everyone. 
Every  Ford  owner  needs  this  practical  book.  You  don't  have  to  guess  about  the  construction 
or  where  the  trouble  is,  as  it  shows  how  to  take  all  parts  apart  and  how  to  locate  and  fix  all 
faults.  The  writer,  Mr.  Pag6,  has  operated  a  Ford  car  for  many  years  and  writes  from  actual 
knowledge.  Among  the  contents  are:  1.  The  Ford  Car:  Its  Parts  and  Their  Functions. 
2.  The  Engine  and  Auxiliary  Groups.  How  the  Engine  Works — The  Fuel  Supply  System — 
The  Carburetor — Making  the  Ignition  Spark — Cooling  and  Lubrication.  3.  Details  of  Chassis. 
Change  Speed  Gear — Power  Transmission — Differential  Gear  Action — Steering  Gear — Front 
Axle — Frame  and  Springs — Brakes.  4.  How  to  Drive  and  Care  for  the  Ford.  The  Control 
System  Explained— Starting  the  Motor — Driving  the  Car — Locating  Roadside  Troubles — 
Tire  Repairs — Oiling -the  Chassis — Winter  Care  of  Car.  5.  Systematic  Location  of  Troubles 
and  Remedies.  Faults  in  Engine — Faults  in  Carburetor — Ignition  Troubles — Cooling  and 
Lubrication  System  Defects — Adjustment  of  Transmission  Gear — General  Chassis  Repairs. 
95  illustrations,  300  pages,  2  large  folding  plates.  Price $1.00 


How  to  Run  an  Automobile.    By  VICTOR  W.  PAGE,  M.S.A.E. 

This  treatise  gives  concise  instructions  for  starting  and  running  all  makes  of  gasoline  auto- 
mobiles, how  to  care  for  them,  and  gives  distinctive  features  of  control.  Describes  every 
step  for  shifting  gears,  controlling  engines,  etc.  Among  the  chapters  contained  are:  I. — 
Automobile  Parts  and  Their  Functions.  II. — General  Starting  and  Driving  Instructions. 
III. — Typical  1917  Control  Systems.  IV. — Care  of  Automobiles.  178  pages.  72  specially 
made  illustrations.  Price • $1.00 


4          THE    NORMAN    W.     HENLEY    PUBLISHING    CO. 
Automobile  Repairing  Made  Easy.    By  VICTOR  W.  PAGE,  M.S.A.E. 

A  comprehensive,  practical  exposition  of  every  phase  of  modern  automobile  repairing  prac- 
tice. Outlines  every  process  incidental  to  motor  car  restoration.  Gives  plans  for  workshop 
construction,  suggestions  for  equipment,  power  needed,  machinery  and  tools  necessary  to 
carry  on  business  successfully.  Tells  how  to  overhaul  and  repair  all  parts  of  all  auto- 
mobiles. Everything  is  explained  so  simpy  that  motorists  and  students  can  acquire  a  full 
working  knowledge  of  automobile  repairing.  This  work  starts  with  the  engine,  then  considers 
carburetion,  ignition,  cooling  and  lubrication  systems.  The  clutch,  change  speed  gearing 
and  transmission  system  are  considered  in  detail.  Contains  instructions  for  repairing  all 
types  of  axles,  steering  gears  and  other  chassis  parts.  Many  tables,  short  cuts  in  figuring 
and  rules  of  practice  are  given  for  the  mechanic.  Explains  fully  valve  and  magneto  timing, 
"tuning"  engines,  systematic  location  of  trouble,  repair  of  ball  and  roller  bearings,  shop  kinks, 
first  aid  to  injured  and  a  multitude  of  subjects  of  interest  to  all  in  the  garage  and  repair  business. 
This  book  contains  special  instructions  on  electric  starting,  lighting  and  ignition  systems,  tire 
repairing  and  rebuilding,  autogenous  welding,  brazing  and  soldering,  heat  treatment  of  steel,  latest 
timing  practice,  eight  and  twelve-cylinder  motors,  etc.  5%x8.  Cloth.  1,056  pages,  1,000  illus- 
trations, 11  folding  plates.  Price $3.00 

WHAT  IS  SAID  OF  THIS  BOOK: 

'"Automobile  Repairing  Made  Easy'  is  the  best  book  on  the  subject  I  have  ever  seen  and 
the  only  book  I  ever  saw  that  is  of  any  value  in  a  garage." — Fred  Jeffrey,  Martinsburg,  Neb. 
"I  wish  to  thank  you  for  sending  me  a  copy  of  'Automobile  Repairing  Made  Easy.'  I  do 
not  think  it  could  be  excelled." — S.  W.  Gisriel,  Director  of  Instruction,  Y.  M.  C.  A.,  Phila- 
delphia, Pa. 


Questions  and  Answers  Relating  to  Modern  Automobile  Construction, 
Driving  and  Repair.     By  VICTOR  W.  PAGE,  M.S.A.E. 

A  practical  self-instructor  for  students,  mechanics  and  motorists,  consisting  of  thirty-seven 
lessons  in  the  form  of  questions  and  answers,  written  with  special  reference  to  the  require- 
ments of  the  non-technical  reader  desiring  easily  understood,  explanatory  matter  relating 
to  all  branches  of  automobiling.  The  subject-matter  is  absolutely  correct  and  explained  in 
simple  language.  If  you  can't  answer  all  of  the  following  questions,  you  need  this  work.  The 
answers  to  these  and  over  2,000  more-  are  to  be  found  in  its  pages.  Give  the  name  of  all  im- 
portant parts  of  an  automobile  and  describe  their  functions.  Describe  action  of  latest  types 
of  kerosene  carburetors.  What  is  the  difference  between  a  "double"  ignition  system  and  a 
"dual"  ignition  system?  Name  parts  of  an  induction  coil.  How  are  valves  l-lmed?  What 
is  an  electric  motor  starter  and  how  does  it  work?  What  are  advantages  of  worm  drive  gear- 
ing? Name  all  important  types  of  ball  and  roller  bearings.  What  is  a  "three-quarter"  float- 
ing axle:  What  is  a  two-speed  axle?  What  is  the  Vulcan  electric  gear  shift?  Name  the  causes 
of  -lost  power  in  automobiles.  Describe  all  noises  due  to  deranged  mechanism  and  give  causes t 
How  can  you  adjust  a  carburetor  by  the  color  of  the  exhaust  gases?  What  causes  "popping" 
in  the  carburetor?  What  tools  and  supplies  are  needed  to  equip  a  car?  How  do  you  drive 
various  makes  of  cars?  What  is  a  differential  lock  and  where  is  it  used?  Name  different 
systems  of  wire  wheel  construction,  etc.,  etc.  A  popular  work  at  a  popular  price.  5^x7^- 
Cloth.  650  pages,  350  illustrations,  3  folding  plates.  Price $1.50 


WHAT  IS  SAID  OF  THIS  BOOK: 

"If  you  own  a  car — get  this  book." — The  Glassworker. 

"Mr.  Page  has  the  faculty  of  making  difficult  subjects  plain  and   understandable." — Bristol 

Press. 

"We  can  name  no  writer  better  qualified  to  prepare  a  book  of  instruction  on  automobiles 

than  Mr.  Victor  W.  Pag6." — Scientific  American. 

"The  best  automobile  catechism  that  has  appeared." — Automobile  Topics. 

"There  are  few  men,  even  with  long  experience,  who  will  not  find  this  book  useful.     Great 

pains  have  been  taken  to  make  it  accurate.     Special  recommendation  must  be  given  to  the 

illustrations,   which  have  been  made  specially  for  the  work.     Such  excellent  books  as  this 

greatly  assist  in  fully  understanding  your  automobile." — Engineering  News. 


The  Automobilist's  Pocket  Companion  and  Expense  Record.    Arranged  by 

VICTOR  W.  PAGE,  M.S.A.E. 

This  book  is  not  only  valuable  as  a  convenient  cost  record  but  contains  much  information  of  value 
to  motorists.  Includes  a  condensed  digest  of  auto  laws  of  all  States,  a  lubrication  schedule, 
hints  for  care  of  storage  battery  and  care  of  tires,  location  of  road  troubles,  anti-freezing 
solutions,  horse-power  table,  driving  hints  and  many  useful  tables  and  recipes  of  interest  to 
all  motorists.  Not  a  technical  book  in  any  sense  of  the  word,  just  a  collection  of  practical 
facts  in  simple  language  for  the  everyday  motorist.  Price  ......  $1.00 


CATALOGUE    OF    GOOD,     PRACTICAL    BOOKS  5 

Modern  Starting,  Lighting  and  Ignition  Systems.    By  VICTOR  W.  PAGE,  M.E. 

This  practical  volume  has  been  written  with  special  reference  to  the  requirements  of  the  non- 
technical reader  desiring  easily  understood,  explanatory  matter,  relating  to  all  types  of  auto- 
mobile ignition,  starting  and  lighting  systems.  It  can  be  understood  by  anyone,  even  without 
electrical  knowledge,  because  elementary  electrical  principles  are  considered  before  any  at- 
tempt is  made  to  discuss  features  of  the  various  systems.  These  basic  principles  are  clearly 
stated  and  illustrated  with  simple  diagrams.  All  the  leading  systems  of  starting,  lighting  and 
ignition  haw  been  described  and  illustrated  with  the  co-operation  of  the  experts  employed  by  the 
manufacturers.  Wiring  diagrams  are  shown  in  both  technical  and  non-technical  forms.  All 
symbols  are  fully  explained.  It  is  a  comprehensive  review  of  modern  starting  and  ignition 
system  practice,  and  includes  a  complete  exposition  of  storage  battery  construction,  care  and 
repair.  All  types  of  starting  motors,  generators,  magnetos,  and  all  ignition  or  lighting  system- 
units  are  fully  explained.  Every  person  in  the  automobile  business  needs  this  volume.  Among 
some  of  the  subjects  treated  are:  I. — Elementary  Electricity;  Current  Production;  Flow; 
Circuits;  Measurements;  Definitions;  Magnetism;  Battery  Action;  Generator  Action.  II. — Battery 
Ignition  Systems.  III. — Magneto  Ignition  Systems.  IV. — Elementary  Exposition  of  Starting 
System  Principles.  V. — Typical  Starting  and  Lighting  Systems;  Practical  Application ;  Wiring 
Diagrams; Auto-lite,  Bijur,  Delco,  Dyneto-Entz,  Gray  and  Davis,  Remy,  U.  S.  L.,  Westinghouse, 
Bosch-Rushmore,  Genemotor,  North-East,  etc.  VI. — Locating  and  Repairing  Troubles  in  Start- 
ing and  Lighting  Systems.  VII. — Auxiliary.  Electric  Systems;  Gear-shifting  by  Electricity; 
Warning  Signals;  Electric  Brake;  Entz-Transmission,  Wagner-Saxon  Circuits,  "Wagner- 
Studebaker  Circuits.  5)^x7^.  Cloth.  530  pages,  2J7  illustrations,  3  folding  plates. 
Price $1.50 


Automobile  Welding  With  the  Oxy-Acetylene  Flame.    By  M.  KEITH  DUNHAM. 

This  is  the  only  complete  book  on  the  "why"  and  "how"  of  Welding  with  the  Oxy-Acetylene 
Flame,  and  from  its  pages  one  can  gain  information  so  that  he  can  weld  anything  that  comes 
along. 

No  one  can  afford  to  be  without  this  concise  book,  as  it  first  explains  the  apparatus  to  be 
used,  and  then  covers  in  detail  the  actual  welding  of  all  automobile  parts.  The  welding  of 
aluminum,  cast  iron,  steel,  copper,  brass  and  malleable  iron  is  clearly  explained,  as  well 
as  the  proper  way  to  burn  the  carbon  out  of  the  combustion  head  of  the  motor.  Among  the 
contents  are:  Chapter  I. — Apparatus  Knowledge.  Chapter  II. — Shop  Equipment  and 
Initial  Procedure.  Chapter  III. — Cast  Iron.  Chapter  IV. — Aluminum.  Chapter  V. — 
Steel.  Chapter  VI. — Malleable  Iron,  Copper,  Brass,  Bronze.  Chapter  VII. — Carbon  Burn- 
ing and  other  Uses  of  Oxygen  and  Acetylene.  Chapter  VIII — How  to  Figure  Cost  of  Weld- 
ing. 167  pages,  fully  illustrated.  Price $1.00 


Storage  Batteries  Simplified.     By  VICTOR  W.  PAG£,  M.S.A.E. 

A  comprehensive  treatise  devoted  entirely  to  secondary  batteries  and  their  maintenance, 
repair  and  use. 

This  is  the  most  up-to-date  book  on  this  subject.  Describes  fully  the  Exide,  Edison,  Gould, 
Willard,  U.  S.  L.  and  other  storage  battery  forms  in  the  types  best  suited  for  automobile, 
stationary  and  marine  work.  Nothing  of  importance  has  been  omitted  that  the  reader  should 
know  about  the  practical  operation  and  care  of  storage  batteries.  No  details  have  been 
slighted.  The  instructions  for  charging  and  care  have  been  made  as  simple  as  possible.  Brief 
Synopsis  of  Chapters:  Chapter  I. — Storage  Battery  Development;  Types  of  Storage  Bat- 
teries; .Lead  Plate  Types;  The  Edison  Cell.  Chapter  II. — Storage  Battery  Construction; 
Plates  and  Girds;  Plante  Plates;  Faur6  Plates;  Non-Lead  Plates;  Commercial  Battery 
Designs.  Chapter  III. — Charging  Methods;  Rectifiers;  Converters;  Rheostats;  Rules 
for  Charging.  Chapter  IV. — Battery  Repairs  and  Maintenance.  Chapter  V. — Industrial 
Application  of  Storage  Batteries;  Glossary  of  Storage  Battery  Terms.  208  Pages.  Very 
Fully  Illustrated.  Price i $1.50  net. 


Motorcycles,  Side  Cars  and  Cyclecars;  their  Construction,  Management 
and  Repair.     By  VICTOR  W.  PAGE,  M.S.A.E. 

The  only  complete  work  published  for  the  motorcyclist  and  cyclecarist.  Describes  fully  all 
leading  types  of  machines,  their  design,  construction,  maintenance,  operation  and  repair. 
This  treatise  outlines  fully  the  operation  of  two-  and  four-cycle  power  plants  and  all  ignition, 
carburetion  and  lubrication  systems  in  detail.  Describes  all  representative  types  of  free 
engine  clutches,  variable  speed  gears  and  power  transmission  systems.  Gives  complete  in- 
structions for  operating  and  repairing  all  types.  Considers  fully  electric  self-starting  and 
lighting  systems,  all  types  of  spring  frames  and  spring  forks  and  shows  leading  control  methods. 
For  those  desiring  technical  information  a  complete  series  of  tables  and  many  formula?  to 
assist  in  designing  are  included.  The  work  tells  how  to  figure  power  needed  to  climb  grades, 
overcome  air  resistance  and  attain  high  speeds.  It  shows  how  to  select  gear  ratios  for  various 
weights  and  powers,  how  to  figure  braking  efficiency  required,  gives  sizes  of  belts  and  chains 
to  transmit  power  safely,  and  shows  how  to  design  sprockets,  belt  pulleys,  etc.  This  work 
also  includes  complete  formulae  for  figuring  horse-power,  shows  how  dynamometer  tests  are 


6    THE  NORMAN  W.  HENLEY  PUBLISHING  CO. 

made,  defines  relative  efficiency  of  air  and  water-cooled  engines,  plain  and  anti-friction  bear- 
ings and  many  other  data  of  a  practical,  helpful,  engineering  nature.  Remember  that  you 
get  this  information  in  addition  to  the  practical  description  and  instructions  which  alone  are 
worth  several  times  the  price  of  the  book.  550  pages.  350  specially  made  illustrations,  5 
folding  plates.  Cloth.  Price  $1.50 

WHAT  IS  SAID  OF  THIS  BOOK: 

"Here  is  a  book  that  should  be  in  the  cycle  repairer's  kit." — American  Blacksmith. 

"The  best  way  for  any  rider  to  thoroughly  understand  his  machine,  is  to  get  a  copy  of  this 

book;    it  is  worth  many  times  its  price." — Pacific  Motorcyclist. 

AUTOMOBILE  AND  MOTORCYCLE  CHARTS 

Chart.  Location  of  Gasoline  Engine  Troubles  Made  Easy— A  Chart  Show- 
ing Sectional  View  of  Gasoline  Engine.  Compiled  by  VICTOR  W.  PAGE, 
M.S.A.E. 

It  shows  clearly  all  parts  of  a  typical  four-cylinder  gasoline  engine  of  the  four-cycle  type. 

It  outlines  distinctly  all  parts  liable  to  give  trouble  and  also  details  the  derangements  apt 

to  interfere  with  smooth  engine  operation. 

Valuable   to   students,   motorists,   mechanics,   repairmen,    garagemen,   automobile   salesmen, 

chauffeurs,    motorboat   owners,    motor-truck    and    tractor   drivers,    aviators,    motor-cyclists, 

and  all  others  who  have  to  do  with  gasoline  power  plants. 

It  simplifies  location  of  all  engine  troubles,  and  while  it  will  prove  invaluable  to  the  novice, 

it  can  be  used  to  advantage  by  the  more  expert.     It  should  be  on  the  walls  of  every  public 

and  private  garage,  automobile  repair  shop,  club  house  or  school.      It  can  be  carried  in  the 

automobile  or  pocket  with  ease,  and  will  insure  againct  loss  of  time  when  engine  trouble 

manifests  itself. 

This  sectional  view  of  engine  is  a  complete  review  of  all  motor  troubles.     It  is  prepared  by  a 

practical  motorist  for  all  who  motor.     More  information  for  the  money  than  ever  before 

offered.    No  details  omitted.    Size  25x38  inches.    Securely  mailed  on  receipt  of        JJ5  CCntS 

Chart.    Location  of  Ford  Engine  Troubles  Made  Easy.    Compiled  by  VICTOR 

W.  PAGE,  M.S.A.E. 

This  shows  clear  sectional  views  depicting  all  portions  of  the  Ford  power  plant  and  auxiliary 
groups.  It  outlines  clearly  all  parts  of  the  engine,  fuel  supply  system,  ignition  group  and 
cooling  system,  that  are  apt  to  give  trouble,  detailing  all  derangements  that  are  liable  to 
make  an  engine  lose  power,  stact  hard  or  work  irregularly.  This  chart  is  valuable  to  students, 
owners,  and  drivers,  as  it  simplifies  location  of  all  engine  faults.  Of  great  advantage  as  a^i 
instructor  for  the  novice,  it  can  be  used  equally  well  by  the  more  expert  as  a  work  of  reference 
and  review.  It  can  be  carried  in  the  tool-box  or  pocket  with  ease  and  will  save  its  cost  in 
labor  eliminated  the  first  time  engine  trouble  manifests  itself.  Prepared  with  special  refer- 
ence to  the  average  man's  needs  and  is  a  practical  review  of  all  motor  troubles  because  it  is  based 
on  the  actual  experience  of  an  automobile  engineer-mechanic  with  the  mechanism  the  chart 
describes.  It  enables  the  non-technical  owner  or  operator  of  a  Ford  car  to  locate  engine 
derangements  by  systematic  search,  guided  by  easily  recognized  symptoms  instead  of  by 
guesswork.  It  makes  the  average  owner  independent  of  the  roadside  repair  shop  when  tour- 
ing. Must  be  seen  to  be  appreciated.  Size  25x38  inches.  Printed  on  heavy  bond  paper. 

Price    .  .  . 25  cents 

Chart.  Lubrication  of  the  Motor  Car  Chassis.  Compiled  by  VICTOR  W. 
PAGE,  M.S.A.E. 

This  chart  presents  the  plan  view  of  a  typical  six-cylinder  chassis  of  standard  design  and  all 
parts  are  clearly  indicated  that  demand  oil,  also  the  frequency  with  which  they  must  be 
lubricated  and  the  kind  of  oil  to  use.  A  practical  chart  for  all  interested  in  motor-car  main- 
tenance. Size  24x38  inches.  Price 25  Cents 

Chart.  Location  of  Carbureton  Troubles  Made  Easy.  Compiled  by  VICTOR 
W.  PAGE,  M.S.A.E. 

This  chart  shows  all  parts  of  a  typical  pressure  feed  fuel  supply  system  and  gives  causes  of 
trouble,  how  to  locate  defects  and  means  of  remedying  them.  Size  24x38  inches. 

Price 25  cents 

Chart.  Location  of  Ignition  System  Troubles  Made  Easy.  Compiled  by 
VICTOR  W.  PAGE,  M.S.A.E. 

In  this  diagram  all  parts  of  a  typical  double  ignition  system  using  battery  and  magneto  current 
are  shown,  and  suggestions  are  given  for  readily  finding  ignition  troubles  and  eliminating 
them  when  found.  Size  24x38  inches.  Price 25  Cents 


CATALOGUE    OF    GOOD,     PRACTICAL     BOOKS  7 

Chart.    Location  of  Cooling  and  Lubrication  System  Faults.    Compiled  by 
VICTOR  W.  PAGE,  M.S.A.E. 

This  composite  diagram  shows  a  typical  automobile  power  plant  using  pump  circulated 
water-cooling  system  and  the  most  popular  lubrication  method.  Gives  suggestions  for  cur- 
ing all  overheating  and  loss  of  power  faults  due  to  faulty  action  of  the  oiling  or  cooling  group. 
Size  24x38  inches.  Price  «}5  cents 

Chart.     Motorcycle  Troubles  Made  Easy.     Compiled  by  VICTOR  W.  PAGE, 
M.S.A.E. 

A  chart  showing  sectional  view  of  a  single-cylinder  gasoline  engine.  This  chart  simplifies 
location  of  all  power-plant  troubles.  A  single-cylinder  motor  is  shown  for  simplicity.  It 
outlines  distinctly  all  parts  liable  to  give  trouble  and  also  details  the  derangements  apt  to 
interfere  with  smooth  engine  operation.  This  chart  will  prove  of  value  to  all  who  have  to  do 
with  the  operation,  repair  or  sale  of  motorcycles.  No  details  omitted.  Size  30x20  inches. 

35  cents 

AVIATION 


Aviation  Engines,  their  Design,  Construction,  Operation  and  Repair.    By 

Lieut.  VICTOR  W.  PAGE,  Aviation  Section,  S.C.U.S.R. 

A  practical  work  containing  valuable  instructions  for  aviation  students,  mechanicians, 
squadron  engineering  officers  and  all  interested  in  the  construction  and  upkeep  of  airplane 
power  plants. 

The  rapidly  increasing  interest  in  the  study  of  aviation,  and  especially  of  the  highly  developed 
internal  combustion  engines  that  make  mechanical  flight  possible,  has  created  a  demand  for  a 
text-book  suitable  for  schools  and  home  study  that  will  clearly  and  concisely  explain  the 
workings  of  the  various  aircraft  engines  of  foreign  and  domestic  manufacture. 
This  treatise,  written  by  a  recognized  authority  on  all  of  the  practical  aspects  of  internal 
combustion  engine  construction,  maintenance  and  repair  fills  the  need  as  no  other  book  does. 
The  matter  is  logically  arranged;  all  descriptive  matter  is  simply  expressed  and  copiously 
illustrated  so  that  anyone  can  understand  airplane  engine  operation  and  repair  even  if  with- 
out previous  mechanical  training.  This  work  is  invaluable  for  anyone  desiring  to  become  an 
aviator  or  aviation  mechanician. 

The  latest  rotary  types,  such  as  the  Gnome,  Monosoupape,  and  Le  Rhone,  are  fully  explained, 
as  well  as  the  recently  developed  Vee  and  radial  types.    The  subjects  of  carburetion,  ignition, 
cooling  and  lubrication  also  are  covered  in  a  thorough  manner.     The  chapters  on  repair  and 
maintenance  are  distinctive  and  found  in  no  other  book  on  this  subject. 
Invaluable  to  the  student,  mechanic  and  soldier  wishing  to  enter  the  aviation  service. 
Not  a  technical  book,  but  a  practical,  easily  understood  work  of  reference  for  all  interested 
in  aeronautical  science.    576  octavo  pages.    253  specially  made  engravings.    Price,  .  $3.00  net 

GLOSSARY  OF  AVIATION  TERMS 

Termes  D* Aviation,  English-French,  French-English.  Compiled  by  Lieuts. 
VICTOR  W.  PAGE,  A.S.,  S.C.U.S.R.,  and  PAUL  MONTARIOL  of  the  French 
Flying  Corps,  on  duty  on  Signal  Corps  Aviation  School,  Mineola,  L.  I. 

A  complete,  well  illustrated  volume  intended  to  facilitate  conversation  between  English- 
speaking  and  French  aviators.  A  very  valuable  book  for  all  who  are  about  to -leave  for  duty 
overseas. 

Approved  for  publication  by  Major  W.  G.  Kilner,  S.C.,  U.S.C.O.  Signal  Corps  Aviation 
School.  Hazlehurst  Field,  Mineola,  L.  I. 

This  book  should  be  in  every  Aviator's  and  Mechanic's  Kit  for  ready  reference.  128  pages. 
Fully  illustrated  with  detailed  engravings.  Price $1.00 

Aviation  Chart.    Location  of  Airplane  Power  Plant  Troubles  Made  Easy. 

By  Lieut.  VICTOR  W.  PAGE,  A.S.,  S.C.U.S.R. 

A  large  chart  outlining  all  parts  of  a  typical  airplane  power  plant,  showing  the  points  where 
trouble  is  apt  to  occur  and  suggesting  remedies  for  the  common  defects.  Intended  espe- 
cially for  Aviators  and  Aviation  Mechanics  on  School  and  Field  Duty.  Price  .  .  50  Cents 

BRAZING  AND  SOLDERING 

Brazing  and  Soldering.     By  JAMES  F.  HOBART. 

The  only  book  that  shows  you  just  bow  to  handle  any  job  of  brazing  or  soldering  that  comes 
along;  it  tells  you  what  mixture  to  use,  how  to  make  a  furnace  if  you  need  one.  Full  of  valu- 
able kinks.  The  fifth  edition  of  this  book  has  just  been  published,  and  to  it  much  new  mat- 
ter and  a  large  number  of  tested  formulae  for  all  kinds  of  solders  and  'fluxes  have  been  added. 
Illustrated.  Price  •  •  25  CCntS 


THE  NORMAN  W.  HENLEY  PUBLISHING  CO. 


CHARTS 


Aviation  Chart.    Location  of  Airplane  Power  Plant  Troubles  Made  Easy. 

By  Lieut.  VICTOR  W.  PAGE,  A.S.,  S.C.U.S.R. 

A  large  chart  outlining  all  parts  of  a  typical  airplane  power  plant,  showing  the  points  where 
trouble  is  apt  to  occur  and  suggesting  remedies  for  the  common  defects.  Intended  especially 
for  Aviators  and  Aviation  Mechanics  on  School  and  Field  Duty.  Price  ....  5Q  cents 

Gasoline  Engine  Troubles  Made  Easy—A  Chart  Showing  Sectional  View  of 
Gasoline  Engine.     Compiled  by  Lieut.  VICTOR  \V.  PAGE,  A.S.,  S.C.U.S.R. 

It  shows  clearly  all  parts  of  a  typical  four-cylinder  gasoline  engine  of  the  four-cycle  type. 

It  outlines  distinctly  all  parts  liable  to  give  trouble  and  also  details  the  derangements  apt 

to  interfere  with  smooth  engine  operation. 

Valuable  to   students,   motorists,   mechanics,   repairmen,   garagemen,    automobile   salesmen, 

chauffeurs,    motor-boat   owners,    motor-truck   and   tractor   drivers,    aviators,    motor-cyclists, 

and  all  others  who  have  to  do  with  gasoline'  power  plants. 

It  simplifies  location  of  all  engine  troubles,  and  while  it  will  prove  invaluable  to  the  novice, 

it  can  be  used  to  advantage  by  the  more  expert.     It  should  be  on  the  walls  of  every  public 

and  private  garage,  automobile  repair  shop,  club  house  or  school.     It  can  be  carried  in  the 

automobile  or  pocket  with  ease  and  will  insure  against  loss  of  time  when  engine  trouble  mani- 

fests itself. 

This  sectional  view  of  engine  is  a  complete  review  of  all  motor  troubles.     It  is  prepared  by  a 

practical  motorist  for  all  who  motor.   No  details  omitted.   Size  25x38  inches.    Price     25  Cents 

Lubrication  of  the  Motor  Car  Chassis. 

This  chart  presents  the  plan  view  of  a  typical  six-cylinder  chassis  of  standard  design  and 
all  parts  are  clearly  indicated  that  demand  oil,  also  the  frequency  with  which  they  must  be 
lubricated  and  the  kind  of  oil  to  use.  A  practical  chart  for  all  interested  in  motor-car  main- 
tenance. Size  24x38  inches.  Price  ...................  25  Cents 


Location  of  Carburetlon  Troubles  Made  Easy. 

This  chart  shows  all"  parts  of  a  typical  pressure  feed  f 

trouble,  how  to  locate  defects  and  means  of  remedying  them.    Siz6  24x38  inches. 


This  chart  shows  all"  parts  of  a  typical  pressure  feed  fuel  supply  system  and  gives  causes  of 

Siz 

25  cents 


Location  of  Ignition  System  Troubles  Made  Easy. 

In  this  chart  all  parts  of  a  typical  double  ignition  system  using  battery  and  magneto  current 
are  shown  and  suggestions  are  given  for  readily  finding  ignition  troubles  and  eliminating 
them  when  found.  Size  24x38  inches.  Price  ...............  25  Cents 

Location  of  Cooling  and  Lubrication  System  Faults. 

This  composite  chart  shows  a  typical  automobile  power  plant  using  pump  circulated  water- 
cooling  system  and  the  most  popular  lubrication  method.  Gives  suggestions  for  curing  all 
overheating  and  loss  of  power  faults  due  to  faulty  action  of  the  oiling  or  cooling  group.  Size 
24x38  inches.  Price  ...........................  25  Cents 

Motorcycle  Troubles  Made  Easy  —  A  Chart  Showing  Sectional  View  of  Single- 
Cylinder  Gasoline  Engine.     Compiled  by  VICTOR  W.  PAGE,  M.S.A.E. 

This  chart  simplifies  location  of  all  power-plant  troubles,  and  will  prove  invaluable  to  all 
who  have  to  do  with  the  operation,  repair  or  sale  of  motorcycles.  No  details  omitted.  Size 
25x38  inches.  Price  .................  .........  25  Cents 

Location  of  Ford  Engine  Troubles  Made  Easy.     Compiled  by  VICTOR  W. 
PAGE,  M.S.A.E. 

This  shows  clear  sectional  views  depicting  all  portions  of  the  Ford  power  plant  and  auxiliary 
groups.  It  outlines  clearly  all  parts  of  the  engine,  fuel  supply  system,  ignition  group  and 
cooling  system,  that  are  apt  to  give  trouble,  detailing  all  derangements  that  are  liable  to 
make  an  engine  lose  power,  start  hard  or  \vork  irregularly.  This  chart  is  valuable  to  students, 
owners,  and  drivers,  as  it  simplifies  location  of  all  engine  faults.  Of  great  advantage  as  an 
instructor  for  the  novice,  it  can  be  used  equally  well  by  the  more  expert  as  a  work  of  reference 
and  review.  It  can  be  carried  in  the  toolbox  or  pocket  with  ease  and  will  save  its  cost  in 
labor  eliminated  the  first  time  engine  trouble  manifests  itself.  Prepared  with  special  refer- 
ence to  the  average  man's  needs  and  is  a  practical  review  of  all  motor  troubles  because  it  is 
based  on  the  actual  experience  of  an  automobile  engineer-mechanic  with  the  mechanism  the 
chart  describes.  It  enables  the  non-technical  owner  or  operator  of  a  Ford  car  to  locate  en- 
gine derangements  by  systematic  search,  guided  by  easily  recognized  symptoms  instead  of 
by  guesswork.  It  makes  the  average  owner  independent  of  the  roadside  repair  shop  when 
touring.  Must  be  seen  to  be  appreciated.  Size  25x38  inches.  Printed  on  he"avy  bond  paper. 

Price    .  ...................  .............    25  cents 


CATALOGUE    OF    GOOD,     PRACTICAL    BOOKS  9 

Modern  Submarine  Chart— with  Two  Hundred  Parts  Numbered  and  Named. 

A  cross-section  view,  showing  clearly  and  distinctly  all  the  interior  of  a  Submarine  of  the 
latest  type.  You  get  more  information  from  this  chart,  about  the  construction  and  opera- 
tion of  a  Submarine,  than  in  any  other  way.  No  details  omitted — everything  is  accurate 
and  to  scale.  It  is  absolutely  correct  in  every  detail,  having  been  approved  by  Naval  En- 
gineers. All  the  machinery  **nd  devices  fitted  in  a  modern  Submarine  Boat  are  shown,  and 
to  make  the  engraving  more  readily  understood  all  the  features  are  shown  in  operative  form, 
with  Officers  and  Men  in  the  act  of  performing  the  duties  assigned  to  them  in  service  con- 
ditions. This  CHART  IS  REALLY  AN  ENCYCLOPEDIA  OF  A  SUBMARINE.  It 
is  educational  and  worth  many  times  its  cost.  Mailed  in  a  Tube  for  25  cents 

Box  Car  Chart. 

A  chart  showing  the  anatomy  of  a  box  car,  having  every  part  of  the  car  numbered  and  ita 
proper  name  given  in  a  reference  list.  Price 25  CCntS 

Gondola  Car  Chart. 

A  chart  showing  the  anatomy  of  a  gondola  car,  having  every  part  of  the  car  numbered  and 
its  proper  reference  name  given  in  a  reference  list.  Price 25  CCntS 

Passenger-Car  Chart. 

A  chart  showing  the  anatomy  of  a  passenger-car,  having  every  part  of  the  car  numbered 
and  its  proper  name  given  in  a  reference  list 25  Cents 

Steel  Hopper  Bottom  Coal  Car. 

A  chart  showing  the  anatomy  of  a  steel  Hopper  Bottom  Coal  Car,  having  every  part  of  the 
car  numbered  and  its  proper  name  given  in  a  reference  list.  Price  .  0 25  COlltS 

Tractive  Power  Chart. 

A  chart  whereby  you  can  find  the  tractive  power  or  drawbar  pull  of  any  locomotive  without 
making  a  figure.  Shows  what  cylinders  are  equal,  how  driving  wheels  and  steam  pressure 
affect  the  power.  What  sized  engine  you  need  to  exert  a  given  drawbar  pull  or  anything  you 
desire  in  this  line.  Price  50  Cents 

Horse-Power  Chart. 

Shows  the  horse-power  of  any  stationary  engine  without  calculation.  No  matter  what  the 
cylinder  diameter  of  stroke,  the  steam  pressure  of  cut-off,  the  revolutions,  or  whether  con- 
densing or  non-condensing,  it's  all  there.  Easy  to  use,  accurate,  and  saves  time  and  calcu- 
lations. Especially  useful  to  engineers  and  designers.  Price 50  cents 

Boiler  Room  Chart.     By  GEO.  L.  FOWLER. 

A  chart — size  14x28  inches — showing  in  isometric  perspective  the  mechanisms  belonging  in 
a  modern  boiler  room.  The  various  parts  are  shown  broken  or  removed,  so  that  the  internal 
construction  is  fully  illustrated.  Each  part  is  given  a  reference  number,  and  these,  with  the 
corresponding  name,  are  given  in  a  glossary  printed  at  the  sides.  This  chart  is  really  a  dic- 
tionary of  the  boiler  room — the  names  of  more  than  200  parts  being  given.  Price  .  25  cents 


COKE 

Modern  Coking  Practice,  Including  Analysis  of  Materials  and  Products. 

By  J.  E.  CHRISTOPHER  and  T.  H.  BYROM. 

This,  the  standard  work  on  the  subject,  has  just  been  revised.  It  is  a  practical  work  for  those 
engaged  in  Coke  manufacture  and  the  recovery  of  By-products.  Fully  illustrated  with  fold- 
ing olates.  It  has  been  the  aim  of  the  authors,  in  preparing  this  book,  to  produce  one  which 
shall  be  of  use  and  benefit  to  those  who  are  associated  with,  or  interested  in,  the  modern 
developments  of  the  industry.  Among  the  Chapters  contained  in  Volume  I  are:  Introduc- 
tion; Classification  of  Fuels;  Impurities  of  Coals;  Coal  Washing;  Sampling  and  Valuation 
of  Coals,  etc.;  Power  of  Fuels;  History  of  Coke  Manufacture;  Developments  in  the  Coke 
Oven  Design;  Recent  Types  of  Coke  Ovens;  Mechanical  Appliances  at  Coke  Ovens;  Chem- 
ical and  Physical  Examination  of  Coke.  Volume  II  covers  fully  the  subject  of  By-Products. 
Price,  per  volume $3.00  net 


10        THE    NORMAN    W.     HENLEY     PUBLISHING     CO. 

COMPRESSED  AIR 

Compressed  Air  in  All  Its  Applications.     By  GARDNER  D.  Hiscox. 

This  is  the  most  complete  book  on  the  subject  of  Air  that  has  ever  been  issued,  and  its  thirty- 
five  chapters  include  about  every  phase  of  the  subject  one  can  think  of.  It  may  be  called 
an  encyclopedia  of  compressed  air.  It  is  written  by  an  expert,  who,  irr  its  665  pages,  has 
dealt  with  the  subject  in  a  comprehensive  manner,  no  phase  of  it  being  omitted.  Includes 
the  physical  properties  of  air  from  a  vacuum  to  its  highest  pressure,  its  thermodynamics, 
compression,  transmission  and  uses  as  a  motive  power,  in  the  Operation  of  Stationary  and 
Portable  Machinery,  in  Mining,  Air  Tools,  Air  Lifts,  Pumping  of  Water,  Acids,  and  Oils; 
the  Air  Blast  for  Cleaning  and  Painting  the  Sand  Blast  and  its  Work,  and  the  Numerous 
Appliances  in  which  Compressed  Air  is  a  Most  Convenient  and  Economical  Transmitter  of 
.Power  for  Mechanical  Work,  Railway  Propulsion,  Refrigeration,  and  the  Various  Uses  to  which 
Compressed  Air  has  been  applied.  Includes  forty-four  tables  of  the  physical  properties  of 
air,  its  compression,  expansion,  and  volumes  required  for  various  kinds  of  work,  and  a  list 
of  patents  on  compressed  air  from  1875  to  date.  Over  500  illustrations,  5th  Edition,  re- 
vised and  enlarged. 

Cloth  bound.     Price $5.00 

Half  Morocco.    Price $(J .50 

CONCRETE 


Concrete  Workers'  Reference  Books.    A  Series  of  Popular  Handbooks  for 
Concrete  Users.     Prepared  by  A.  A.  HOUGHTON 50  cents 

The  author,  in  preparing  this  Series,  has  not  only  treated  on  the  usual  types  of  construction,  but 
explains  and  illustrates  molds  and  systems  that  are  not  patented,  but  which  are  equal  in  value 
and  often  superior  to  those  restricted  by  patents.  These  molds  are  very  easily  and  cheaply  con- 
structed and  embody  simplicity,  rapidity  of  operation,  and  the  most  successful  results  in  the  molded 
concrete.  Each  of  these  books  is  fully  illustrated,  and  the  subjects  are  exhaustively  treated  in  plain 
English. 

Concrete  Wall  Forms.     By  A.  A.  HOUGHTON. 

A  new  automatic  wall  clamp  is  illustrated  with  working  drawings.  Other  types  of  wall  forms, 
clamps,  separators,  etc.,  are  also  illustrated  and  explained.  .(No.  1  of  Series)  Price  50  Cents 

Concrete  Floors  and  Sidewalks.    By  A.  A.  HOUGHTON. 

The  molds  for  molding  squares,  hexagonal  and  many  other  styles  of  mosaic  floor  and  side- 
walk blocks  are  fully  illustrated  and  explained.  (No.  2  of  Series)  Price 50  Cents 

Practical  Concrete  Silo  Construction.    By  A.  A.  HOUGHTON. 

Complete  working  drawings  and  specifications  are  given  for  several  styles  of  concrete  silos, 
with  illustrations  of  molds  for  monolithic  and  block  silos.  The  tables,  data,  and  information 
presented  in  this  book  are  of  the  utmost  value  in  planning  and  constructing  all  forms  of  con- 
crete silos.  (No.  3  of  Series)  Price  50  Cents 

Molding  Concrete  Chimneys,  Slate  and  Roof  Tiles.    By  A.  A.  HOUGHTON. 

The  manufacture  of  all  types  of  concrete  slate  and  roof  tile  is  fully  treated.  Valuable  data 
on  all  forms  of  reinforced  concrete  roofs  are  contained  within  its  pages.  The  construction 
of  concrete  chimneys  by  block  and  monolithic  systems  is  fully  illustrated  and  described.  A 
number  of  ornamental  designs  of  chimney  construction  with  molds  are  shown  in  this  valuable 
treatise.  (No.  4  of  Series.)  Price 50  Cents 

Molding  and  Curing  Ornamental  Concrete.    By  A.  A.  HOUGHTON. 

The  proper  proportions  of  cement  and  aggregates  for  various  finishes,  also  the  method  of 
thoroughly  mixing  and  placing  in  the  molds,  are  fully  treated.  An  exhaustive  treatise  on 
this  subject  that  every  concrete  worker  will  find  of  daily  use  and  value.  (No.  5  of  Series.) 

Price 50  cents 

Concrete  Monuments,  Mausoleums  and  Burial  Vaults.    By  A.  A.  HOUGHTON. 

The  molding  of  concrete  monuments  to  imitate  the  most  expensive  cut  stone  is  explained 
in  this  treatise,  with  working  drawings  of  easily  built  molds.  Cutting  inscriptions  and  de- 
signs are  also  fully  treated.  (No.  6  of  Series.)  Price 50  Cents 

Molding    Concrete   Bathtubs,    Aquariums   and   Natatoriums.     By   A.    A. 

HOUGHTON. 

Simple  molds  and  instruction  are  given  for  molding  many  styles  of  concrete  bathtubs,  swim- 
ming-pools, etc.  These  molds  are  easily  built  and  permit  rapid  and  successful  work.  (No.  7 
of  Series.)  Price 50  Cents 


CATALOGUE    OF    GOOD,    PRACTICAL    BOOKS          11 
Concrete  Bridges,  Culverts  and  Sewers.    By  A.  A.  HOUGHTON. 

A  number  of  ornamental  concrete  bridges  with  illustrations  of  molds  are  given.  A  collapsible 
center  or  core  for  bridges,  culverts  and  sewers  is  fully  illustrated  with  detailed  instructions 
for  building.  (No.  8  of  Series.)  Price 50  CCntS 

Constructing  Concrete  Porches.    By  A.  A.  HOUGHTON. 

A  number  of  designs  with  working  drawings  of  molds  are  fully  explained  so  any  one  can  ea«ily 
construct  different  styles  of  ornamental  concrete  porches  without  the  purchase  of  expensive 
molds.  (No.  9  of  Series.)  Price 50  cents 

Molding  Concrete  Flower-Pots,  Boxes,  Jardinieres,  Etc.    By  A.  A.  HOUGHTON. 

The  molds  for  producing  many  original  designs  of  flower-pots,  urns,  flower-boxes,  jardinieres, 
etc.,  are  fully  illustrated  and  explained,  so  the  worker  can  easily  construct  and  operate  same. 
(No.  10  of  Series.)  Price 50  cents 

Molding  Concrete  Fountains  and  Lawn  Ornaments.    By  A.  A.  HOUGHTON. 

The  molding  of  a  number  of  designs  of  lawn  seats,  curbing,  hitching  posts,  pergolas,  sun  dials 
and  other  forms  of  ornamental  concrete  for  the  ornamentation  of  lawns  and  gardens,  is  fully 
illustrated  and  described.  (No.  11  of  Series.)  Price 50  Cents 

Concrete  from  Sand  Molds*    By  A.  A.  HOUGHTON. 

A  Practical  Work  treating  on  a  process  which  has  heretofore  been  held  as  a  trade  secret  by 
the  few  who  possessed  it,  and  which  will  successfully  mold  every  and  any  class  of  ornamental 
concrete  work.  The  process  of  molding  concrete  with  sand  molds  is  of  the  utmost  practical 
value,  possessing  the  manifold  advantages  of  a  low  cost  of  molds,  the  ease  and  rapidity  of 
operation,  perfect  details  to  all  ornamental  designs,  density  and  increased  strength  of  the 
concrete,  perfect  curing  of  the  work  without  attention  and  the  easy  removal  of  the  molds 
regardless  of  any  undercutting  the  design  may  have.  192  pages.  Fully  illustrated 
Price $2.00 

Ornamental  Concrete  without  Molds.    By  A.  A.  HOUGHTON. 

The  process  for  making  ornamental  concrete  without  molds  has  long  been  held  as  a  secret, 
and  now,  for  the  first  time,  this  process  is  given  to  the  public.  The  book  reveals  the  secret 
and  is  the  only  book  published  which  explains  a  simple,  practical  method  whereby  the  con- 
crete worker  is  enabled,  by  employing  wood  and  metal  templates  of  different  designs,  to  mold 
or  model  in  concrete  any  Cornice,  Archivolt,  Column,  Pedestal,  Base  Cap,  Urn  or  Pier  in  a 
monolithic  form — right  upon  the  job.  These  may  be  molded  in  units  or  blocks  and  then  built 
up  to  suit  the  specifications  demanded.  This  work  :s  fully  illustrated,  with  detailed  engrav- 
ings. Price .$3.00 

Concrete  for  the  Farm  and  in  the  Shop.    By  H.  COLIN  CAMPBELL,  C.E.,  E.M. 

"Concrete  for  the  Farm  and  in  the  Shop"  is  a  new  book  from  cover  to  cover,  illustrating  and 
describing  in  plain,  simple  language  many  of  the  numerous  applications  of  concrete  within 
the  range  of  the  home  worker.  Among -the  subjects  treated  are:  Principles  of  Reinforcing; 
Methods  of  Protecting  Concrete  so  as  to  Insure  Proper  Hardening;  Home-made  Mixers; 
Mixing  by  Hand  and  Machine;  Form  Construction,  Described  and  Illustrated  by  Draw- 
ings and  Photographs;  Construction  of  Concrete  Walls  and  Fences;  Concrete  Fence  Posts; 
Concrete  Gate  Posts;  Corner  Posts;  Clothes  Line  Posts;  Grape  Arbor  Posts;  Tanks; 
Troughs;  Cisterns;  Hog  Wallows;  Feeding  Floors  and  Barnyard  Pavements;  Foundations; 
Well  Curbs  and  Platforms;  Indoor  Floors;  Sidewalks;  Steps;  Concrete  Hotbeds  and  Cold 
Frames;  Concrete  Slab  Roofs;  Walls  for  Buildings;  Repairing  Leaks  in  Tanks  and  Cisterns; 
and  all  topics  associated  with  these  subjects  as  bearing  upon  securing  the  best  results  from 
concrete  are  dwelt  upon  at  sufficient  length  in  plain  every-day  English  so  that  the  inexperi- 
enced person  desiring  to  undertake  a  piece  of  concrete  construction  can,  by  following  the 
directions  set  forth  in  this  book,  secure  100  per  cent,  success  every  time.  A  number  of  con- 
venient and  practical  tables  for  estimating  quantities,  and  some  practical  examples,  are  also 
given.  (5x7.)  149  pages.  51  illustrations.  Price 75  Cents 

Popular  Handbook  for  Cement  and  Concrete  Users.    By  MYRON  H.  LEWIS. 

This  is  a  concise  treatise  of  the  principles  and  methods  employed  in  the  manufacture  and  use 
of  cement  in  all  classes  of  modern  works.  The  author  has  brought  together  in  this  work  all 
the  salient  matter  of  interest  to  the  user  of  concrete  and  its  many  diversified  products.  The 
matter  is  presented  in  logical  and  systematic  order,  clearly  written,  fully  illustrated  and  free 
from  involved  mathematics.  Everything  of  value  to  the  concrete  user  is  given,  including 
kinds  of  cement  employed  in  construction,  concrete  architecture,  inspection  and  testing, 
waterproofing,  coloring  and  painting,  rules,  tables,  working  and  cost  data.  The  book  com- 
prises thirty-three  chapters,  as  follow:  Introductory.  Kinds  of  Cement  and  How  They 
are  Made.  Properties.  Testing  and  Requirements  of  Hydraulic  Cement.  Concrete  and  Its 
Properties.  Sand,  Broken  Stone  and  Gravel  for  Concrete.  How  to  Proportion  the  Materials. 
How  to  Mix  and  Place  Concrete.  Forms  of  Concrete  Construction.  The  Architectural  and 
Artistic  Possibilities  of  Concrete.  Concrete  Residences.  Mortars,  Plasters  and  Stucco, 
and  How  to  Use  Them.  The  Artistic  Treatment  of  Concrete  Surfaces.  Concrete  Building 


12        THE    NORMAN    W.    HENLEY    PUBLISHING    CO. 

Blocks.  The  Making  of  Ornamental  Concrete.  Concrete  Pipes,  Fences,  Posts,  etc.  Essen- 
tial Features  and  Advantages  of  Reenforced  Concrete.  How  to  Design  Reenforced  Con- 
crete Beams,  Slabs  and  Columns.  Explanations  of  the  Methods  and  Principles  in  Designing 
Reenforced  Concrete,  Beams  and  Slabs.  Systems  of  Reenforcement  Employed.  Reen- 
forced Concrete  in  Factory  and  General  Building  Construction.  Concrete  in  Foundation  Work. 
Concrete  Retaining  Walls,  Abutments  and  Bulkheads.  Concrete  Arches  and  Arch  Bridges. 
Concrete  Beam  and  Girder  Bridges.  Concrete  in  Sewerage  and  Draining  Works.  Concrete 
Tanks,  Dams  and  Reservoirs.  Concrete  Sidewalks,  Curbs  and  Pavements.  Concrete  in 
Railroad  Construction.  The  Utility  of  Concrete  on  the  Farm'.  The  Waterproofing  of  Con- 
crete Structures.  Grout  of  Liquid  Concrete  and  Its  Use.  Inspection  of  Concrete  Work. 
Cost  of  Concrete  Work.  Some  of  the  special  features  of  the  book  are:  1. — The  Attention 
Paid  to  the  Artistic  and  Architectural  Side  of  Concrete  Work.  2. — The  Authoritative  Treat- 
ment of  the  Problem  of  Waterproofing  Concrete.  3. — An  Excellent  Summary  of  the  Rules 
to  be  Followed  in  Concrete  Construction.  4. — The  Valuable  Cost  Data  and  Useful  Tables 
given.  A  valuable  Addition  to  the  Library  of  Every  Cement  and  Concrete  User.  Price 

WHAT  IS  SAID  OF. THIS  BOOK: 

"The  field  of  Concrete  Construction  is  well  covered  and  the  matter  contained  is  well  within 
the  understanding  of  any  person." — Engineering-Contracting. 

"Should  be  on  the  bookshelves  of  every  contractor,  engineer,  and  architect  in  the  land." — 
National  Builder. 

Waterproofing  Concrete.     By  MYRON  H.  LEWIS. 

Modern  Methods  of  Waterproofing  Concrete  and  Other  Structures.  A  condensed  statement 
of  the  Principles,  Rules,  and  Precautions  to  be  Observed  in  Waterproofing  and  Dampproofing 
Structures  and  Structural  Materials.  Paper  binding.  Illustrated.  Price  ....  50  Cents 

DICTIONARIES 

Aviation    Terms,    Termes    D'Aviation,    English-French,    French-English. 

Compiled  by  Lieuts.  VICTOR  W.  PAGE,  A.S.,  S.C.U.S.R.,  and  PAUL  MON- 
TARIOL,  of  the  French  Flying  Corps,  on  duty  on  Signal  Corps  Aviation  School, 
Mineola,  L.  I. 

The  lists  contained  are  confined  to  essentials,  and  special  folding  plates  are  included  to  show 
all  important  airplane  parts.  The  lists  are  divided  in  four  sections  as  follows:  1. — Flying 
Field  Terms.  2.-^The  Airplane.  3. — The  Engine.  4. — Tools  and  Shop  Terms. 
A  complete,  well  illustrated  volume  intended  to  facilitate  conversation  between  English-speak- 
ing and  French  aviators.  A  very  valuable  book  for  all  who  are  about  to  leave  for  duty  over- 
seas. 

Approved  for  publication  by  Major  W.  G.  Kilner,  S.C.,  TJ.S.C.O.  Signal  Corps  Aviation  School, 
Hazelhurst  Field,  Mineola,  L.  I.  This  book  should  be  in  every  Aviator's  and  Mechanic's  Kit 
for  ready  reference.  128  pages,  fully  illustrated,  with  detailed  engravings.  Price  .  .  $1.00 

Standard  Electrical  Dictionary.    By  T.  O'CoNOR  SLOANE. 

An  indispensable  work  to  all  interested  in  electrical  science.  Suitable  alike  for  the  student 
and  professional.  A  practical  handbook  of  reference  containing  definitions  of  about  5,000 
distinct  words,  terms  and  phrases.  The  definitions  are  terse  and  concise  and  include  every 
term  used  in  electrical  science.  Recently  issued.  An  entirely  new  edition.  Should  be  in 
the  possession  of  all  who  desire  to  keep  abreast  with  the  progress  of  this  branch  of  science. 
Complete,  concise  and  convenient.  682  pages,  393  illustrations.  Price $3.00 

DIES— METAL  WORK 

Dies:  Their  Construction  and  Use  for  the  Modern  Working  of  Sheet  Metals. 

By  J.  V.  WOODWORTH. 

A  most  useful  book,  and  one  which  should  be  in  the  hands  of  all  engaged  in  the  press  working 
of  metals;  treating  on  the  Designing,  Constructing,  and  Use  of  Tools,  Fixtures  and  Devices, 
together  with  the  manner  in  which  they  should  be  used  in  the  Power  Press,  for  the  cheap  and 
rapid  production  of  the  great  variety  of  sheet-metal  articles  now  in  use.  It  is  designed 
as  a  guide  to  the  production  of  sheet-metal  parts  at  the  minimum  of  cost  with  the 
maximum  of  output.  The  hardening  and  tempering  of  Press  tools  and  the  classes  of  work 
which  may  be  produced  to  the  best  advantage  by  the  use  of  dies  in  the  power  press  are  fully 
treated.  Its  515  illustrations  show  dies,  press  fixtures  and  sheet-metal  working  devices,  the 
descriptions  of  which  are  so  clear  and  practical  that  all  metal-working  mechanics  will  be  able 
to  understand  how  to  design,  construct  and  use  them.  Many  of  the  dies  and  press  fixtures 
treated  were  either  constructed  by  the  author  or  under  his  supervision.  Others  were  built  by 
•  skilful  mechanics  and  are  in  use  in  large  sheet-metal  establishments  and  machine  shops. 
6th  Revised  and  Enlarged  Edition.  Price $3.00 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    13 

Punches,  Dies  and  Tools  for  Manufacturing  in  Presses.    By  J.  V.  WOOD- 
WORTH. 

This  work  is  a  companion  volume  to  the  author's  elementary  work  entitled  "Dies:  Their 
Construction  and  Use."  It  does  not  go  into  the  details  of  die-making  to  the  extent  of  the 
author's  previous  book,  but  gives  a  comprehensive  review  of  the  field  of  operations  carried  on 
by  presses.  A  large  part  of  the  information  given  has  been  drawn  from  the  author's  personal 
experience.  It  might  well  be  termed  an  Encyclopedia  of  Die-Making,  Punch-Making,  Die- 
Sinking,  Sheet-Metal  Working,  and  Making  of  Special  Tools,  Sub-presses,  Devices  and  Mechani- 
cal Combinations  for  Punching,  Cutting,  Bending,  Forming,  Piercing,  Drawing,  Compressing 
and  Assembling  Sheet-Metal  Parts,  and  also  Articles*  of  other  Materials  in  Machine  Tools. 
2d  Edition.  Price $4.00 

Drop   Forging,    Die-Sinking   and   Machine-Forming   of   Steel.    By   J.   V. 

WOODWORTH. 

This  is  a  practical  treatise  on  Modern  Shop  Practice,  Processes,  Methods,  Machine  Tools, 
and  Details  treating  on  the  Hot  and  Cold  Machine-Forming  of  Steel  and  Iron  into  Finished 
Shapes:  together  with  Tools,  Dies,  and  Machinery  involved  in  the  manufacture  of  Duplicate 
Forgings  and  Interchangeable  Hot  and  Cold  Pressed  Parts  from  Bar  and  Sheet  Metal.  This 
book  fills  a  demand  of  long  standing  for  information  regarding  drop-forgings,  die-sinking  and 
machine-forming  of  steel  and  the  shop  practice  involved,  as  it  actually  exists  in  the  modern 
drop-forging  shop.  The  processes  of  die-sinking  and  force-making,  which  are  thoroughly 
described  and  illustrated  in  this  admirable  work,  are  rarely  to  be  found  explained  in  such  a 
clear  and  concise  manner  as  is  here  set  forth.  The  process  of  die-sinking  relates  to  the  engrav- 
ing or  sinking  of  the  female  or  lower  dies,  such  as  are  used  for  drop-forgings,  hot  and  cold 
machine-forging,  s wedging,  and  the  press  working  of  metals.  The  process  of  force-making 
relates  to  the  engraving  or  raising  of  the  male  or  upper  dies  used  in  producing  the  lower  dies 
for  the  press-forming  and  machine-forging  of  duplicate  parts  of  metal. 

In  addition  to  the  arts  above  mentioned  the  book  contains  explicit  information  regarding  the 
drop-forging  and  hardening  plants,  designs,  conditions,  equipment,  drop  hammers,  forging 
machines,  etc.,  machine  forging,  hydraulic  forging,  autogenous  welding  and  shop  practice. 
The  book  contains  eleven  chapters,  and  the  information  contained  in  these  chapters  is  just 
what  will  prove  most  valuable  to  the  forged-metal  worker.  All  operations  described  in  the 
work  are  thoroughly  illustrated  by  means  of  perspective  half-tones  and  outline  sketches  of 
the  machinery  employed.  300  detailed  illustrations.  Price $2.50 

,    DRAWING— SKETCHING  PAPER 

Practical  Perspective.    By  RICHARDS  and  COLVIN. 

Shows  just  how  to  make  all  kinds  of  mechanical  drawings  in  the  only  practical  perspective 
isometric.  Makes  everything  plain,  so  that  any  mechanic  can  understand  a  sketch  or  drawing 
in  this  way.  Saves  time  in  the  drawing  room,  and  mistakes  in  the  shops.  Contains  practical 
examples  of  various  classes  of  work.  4th  Edition.  Price 50  cents 

Linear  Perspective  Self-Taught.    By  HERMAN  T.  C.  KRAUS. 

This  work  gives  the  theory  and  practice  of  linear  perspective,  as  used  in  architectural,  engineer- 
ing and  mechanical  drawings.  Persons  taking  up  the  study  of  the  subject  by  themselves  will 
be  able,  by  the  use  of  the  instruction  given,  to  readily  grasp  the  subject,  and  by  reasonable 
practice  become  good  perspective  draftsmen.  The  arrangement  of  the  book  is  good;  the  plate 
is  on  the  left-hand,  while  the  descriptive  text  follows  on  the  opposite  page,  so  as  to  be  readily 
referred  to.  The  drawings  are  on  sufficiently  large  scale  to  show  the  work  clearly  and  are 
plainly  figured.  There*is  included  a  self-explanatory  chart  which  gives  all  information  neces- 
sary for  the  thorough  understanding  of  perspective.  This  chart  alone  is  worth  many  times 
over  the  price  of  the  book.  2d  Revised  and  Enlarged  Edition.  Price $2.50 

Self-Taught  Mechanical  Drawing  and  Elementary  Machine  Design.    By 

F.  L.  SYLVESTER,  M.E.,  Draftsman,  with  additions  by  ERIK  OBERG,  associate 
editor  of  "Machinery." 

This  is  a  practical  treatise  on  Mechanical  Drawing  and  Machine  Design,  comprising  the  first 
principles  of  geometric  and  mechanical  drawing,  workshop  mathematics,  mechanics,  strength 
of  materials  and  the  calculations  and  design  of  machine  details.  The  author's  aim  has  been 
to  adapt  this  treatise  to  the  requirements  of  the  practical  mechanic  and  young  draftsman 
and  to  present  the  matter  in  as  clear  and  concise  a  manner  as  possible.  To  meet  the  demands 
of  this  class  of  students,  practically  all  the  important  elements  of  machine  design  have  been 
dealt  with,  and  in  addition  algebraic  formulas  have  been  explained,  and  the  elements  of 
trigonometry  treated  in  the  manner  best  suited  to  the  needs  of  the  practical  man.  The  book 
isdivided  into  20  chapters,  and  in  arranging  the  material,  mechanical  drawing,  pure  and  simple, 
has  been  taken  up  first,  as  a  thorough  understanding  of  the  principles  of  representing  objects 
facilitates  the  further  study  of  mechanical  subjects.  This  is  followed  by  the  mathematics 
necessary  for  the  solution  of  the  problems  in  machine  design  which  are  presented  later,  and  a 
practical  introduction  to  theoretical  mechanics  and  the  strength  of  materials.  The  various 
elements  entering  into  machine  design,  such  as  cams,  gears,  sprocket-wheels,  cone  pulleys, 
bolts,  screws,  couplings,  clutches,  shafting  and  fly-wheels,  have  been  treated  in  such  a  way 
as  to  make  possible  the  use  of  the  work  as  a  text-book  for  a  continuous  course  of  study.  It 
is  easily  comprehended  and  assimilated  even  by  students  of  limited  previous  training.  330 
pages,  215  engravings.  Price $3.00 


16        THE     NORMAN    W.     HENLEY    PUBLISHING     CO. 
How  to  Become  a  Successful  Electrician.    By  Prof.  T.  O'CONOR  SLOANE. 

Every  young  man  who  wishes  to  become  a  successful  electrician  should  read  this  book.  It 
.  tells  in  simple  language  the  surest  and  easiest  way  to  become  a  successful  electrician.  The 
studies  to  be  followed,  methods  of  work,  field  of  operation  and  the  requirements  of  the  suc- 
cessful electrician  are  pointed  out  and  fully  explained.  Every  young  engineer  will  find  this  an 
excellent  stepping  stone  to  more  advanced  works  on  electricity  which  he  must  master  before 
success  can  be  attained.  Many  young  men  become  discouraged  at  the  very  outstart  by  at- 
tempting to  read  and  study  books  that  are  far  beyond  their  comprehension.  This  book  serves 
as  the  connecting  link  between  the  rudiments  taught  in  the  public  schools  and  the  real  study 
of  electricity.  It  is  interesting  from  cover  to  cover.  18th  Revised  Edition,  just  issued.  205 
Illustrated.  Price $1.00 


Management  of  Dynamos.    By  LUMMIS-PATERSON. 

A  handbook  of  theory  and  practice.  This  work  is  arranged  in  three  parts.  The  first  part 
covers  the  elementary  theory  of  the  dynamo.  The  second  part,  the  construction  and  action 
of  the  different  classes  of  dynamos  in  common  use  are  described;  while  the  third  .part  relates 
to  such  matters  as  affect  the  nractical  management  and  working  of  dynamos  and  motors. 
4th  Edition.  292  pages,  117  illustrations.  Price $1.50 

Standard  Electrical  Dictionary.    By  T.  O' CONOR  SLOANE. 

An  indispensable  work  to  all  interested  in  electrical  science.  Suitable  alike  for  the  student 
and  professional.  A  practical  handbook  of  reference  containing  definitions  of  about  5,000 
distinct  words,  terms  and  phrases.  The  definitions  are  terse  and  concise  and  include  every 
term  used  in  electrical  science.  .  Recently  issued.  An  entirely  new  edition.  Should  be  in  the 
possession  of  all  who  desire  to  keep  abreast  with  the  progress  of  this  branch  of  science.  In 
its  arrangement  and  typography  the  book  is  very  convenient.  The  word  or  term  defined  is 
•  printed  in  black-faced  type,  which  readily  catches  the  eye,  while  the  body  of  the  page  is  in 
smaller  but  distinct  type.  The  definitions  are  well  worded,  and  so  as  to  be  understood  by  the 
non-technical  reader.  The  general  plan  seems  to  be  to  give  an  exact,  concise  definition,  and 
then  amplify  and  explain  in  a  more  popular  way.  Synonyms  are  also  given,  and  references 
to  other  words  and  phrases  are  made.  A  very  complete  and  accurate  index  of  fifty  pages 
is  at  the  end  of  the  volume;  and  as  this  index  contains  all  synonyms,  and  as  all  phrases  art 
indexed  in  every  reasonable  combination  of  words,  reference  to  the  proper  place  in  the  body 
of  the  book  is  readily  made.  It  is  difficult  to  decide  how  far  a  book  of  this  character  is  to 
keep  the  dictionary  form,  and  to  what  extent  it  may  assume  the  encyclopedia  form.  For 
some  purposes,  concise,  exactly  worded  definitions  are  needed;  for  other  purposes,  more 
extended  descriptions  are  required.  This  book  seeks  to  satisfy  both  demands,  and  does  it 
with  considerable  success.  682  pages,  393  illustrations.  12th  Edition. 
Price $3.00 

Storage  Batteries  Simplified.    By  VICTOR  W.  PAGE,  M.E. 

A  complete  treatise  on  storage  battery  operating  principles,  repairs'  and  applications. 
The  greatly  increasing  application  of  storage  batteries  in  modern  engineering  and  mechanical 
work  has  created  a  demand  for  a  book  that  will  consider  this  subject  completely  and  exclu- 
sively. This  is  the  most  thorougli  and  authoritative  treatise  ever  published  on  this  subject. 
It  is  written  in  easily  understandable,  non-technical  language  so  that  any  one  may  grasp 
the  basic  principles  of  storage  battery  action  as  well  as  their  practical  industrial  applications. 
All  electric  and  gasoline  automobiles  use  storage  batteries.  Every  automobile  repairman, 
dealer  or  salesman  should  have  a  good  knowledge  of  maintenance  and  repair  of  these  impor- 
tant elements  of  the  motor  car  mechanism.  This  book  not  only  tells  how  to  charge,  care  for 
and  rebuild  storage  batteries  but  also  outlines  all  the  industrial  uses.  Learn  how  they  run 
street  cars,  locomotives  and  factory  trucks.  Get  an  understanding  of  the  important  functions 
they  perform  in  submarine  boats,  isolated  lighting  plants,  railway  switch  and  signal  systems, 
marine  applications,  etc.  This  book  tells  how  they  are  used  in  central  station  standby  service, 
for  starting  automobile  motors  and  in  ignition  systems.  Every  practical  use  of  the  modern 
storage  battery  is  outlined  in  this  treatise.  320  pages,  fully  illustrated.  Price  .  .  .  $1.50 

Switchboards.    By  WILUAM  BAXTER,  JR. 

This  book  appeals  to  every  engineer  and  electrician  who  wants  to  know  the  practical  side 
of  things.  It  takes  up  all  sorts  and  conditions  of  dynamos,  connections  and  circuits,  and 
shows  by  diagram  and  illustration  just  how  the  switchboard  should  be  connected.  Includes 
direct  and  alternating  current  boards,  als'o  those  for  arc  lighting,  incandescent  and  power 
circuits.  Special  treatment  on  high  voltage  boards  for  power  transmission.  2nd  Edition. 
190  pages,  Illustrated.  Price $1.50 

Telephone  Construction,  Installation,  Wiring,  Operation  and  Maintenance. 

By  W.  H.  RADCLIFFE  and  H.  C.  GUSHING. 

This  book  is  intended  for  the  amateur,  the  wireman,  or  the  engineer  who  desires  to  establish 
a  means  of  telephonic  communication  between  the  rooms  of  his  home,  office,  or  shop.  It 
deals  only  with  such  things  as  may  be  of  use  to  him  rather  than  with  theories. 
Gives  the  principles  of  construction  and  operation  of  both  the  Bell  and  Independent  instru- 
ments; approved  methods  of  installing  and  wiring  them;  the  means  of  protecting  them 
from  lightning  and  abnormal  currents;  their  connection  together  for  operation  as  series  or 
bridging  stations;  and  rules  for  their  inspection  and  maintenance.  Line  wiring  and  the  wiring 
and  operation  of  special  telephone  systems  are  also  treated.  Intricate  mathematics  are 
avoided,  and  all  apparatus,  circuits  and  systems  are  thoroughly  described.  The  appendix 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    17 

contains  definitions  of  units  and  terms  used  in  the  text.  Selected  wiring  tables,  which  are  very 
helpful,  are  also  included.  Among  the  subjects  treated  are  Construction,  Operation,  and 
Installation  of  Telephone  Instruments;  Inspection  and  Maintenance  of  Telephone  Instru- 
ments; Telephone  Line  Wiring;  Testing  Telephone  Line  Wires  and  Cables;  Wiring  and 
Operation  of  Special  Telephone  Systems,  etc.  2nd  Edition,  Revised  and  Enlarged.  223 
pages,  154  illustrations $1.00 

Wireless   Telegraphy   and   Telephony   Simply   Explained.    By  ALFRED   P. 
MORGAN. 

This  is  undoubtedly  one  of  the  most  complete  and  comprehensible  treatises  on  the  subject 
ever  published,  and  a  close  study  of  its  pages  will  enable  one  to  master  all  the  details  of  tht, 
wireless  transmission  of  messages.  The  author  has  filled  a  long-felt  want  and  has  succeeded 
in  furnishing  a  lucid,  comprehensible  explanation  in  simple  language  of  the  theory  and  practice 
of  wireless  telegraphy  and  telephony. 

Among  the  contents  are:  Introductory;  Wireless  Transmission  and  Reception — The  Aerial 
System,  Earth  Connections — The  Transmitting  Apparatus,  Spark  Coils  and  Transformers, 
Condensers,  Helixes,  Spark  Gaps,  Anchor  Gaps,  Aerial  Switches — The  Receiving  Apparatus, 
Detectors,  etc. — Tuning  and  Coupling,  Tuning  Coils,  Loose  Couplers,  Variable  Condensers, 
Directive  Wave  Systems — Miscellaneous  Apparatus,  Telephone  Receivers,  Range  of  Stations, 
Static  Interference — Wireless  Telephones,  Sound  and  Sound  Waves,  The  Vocal  Cords  and 
Ear — Wireless  Telephone,  How  Sounds  Are  Changed  into  Electric  Waves — ^Wireless  Tele- 
phones, The  Apparatus — Summary.  154  pages,  156  engravings.  Price $1.00 

Wiring  a  House.     By  HERBERT  PRATT. 

Shows  a  house  already  built;  tells  just  how  to  start  about  wiring  it;  where  to  begin;  what 
wire  to  use;  how  to  run  it  according  to  Insurance  Rules;  in  fact,  just  the  information  you 
need.  Directions  apply  equally  to  a  shop.  4th  Edition.  Price £5  CClllS 

FACTORY  MANAGEMENT,  ETC. 

Modern  Machine  Shop  Construction,  Equipment  and  Management.    By 

O.  E.  PERRIGO,  M.E. 

The  only  work  published  that  describes  the  modern  machine  shop  or  manufacturing  plant 
from  the  time  the  grass  is  growing  on  the  site  intended  for  it  until  the  finished  product  is 
shipped.  By  a  careful  study  of  its  thirty-two  chapters  the  practical  man  may  economically 
build,  efficiently  equip,  and  successfully  manage  the  modern  machine  shop  or  manufacturing 
establishment.  Just  the  book  needed  by  those  contemplating  the  erection  of  modern  shop 
buildings,  the  rebuilding  and  reorganization  of  old  ones,  or  the  introduction  of  modern  shop 
methods,  time  and  cost  systems.  It  is  a  book  written  and  illustrated  by  a  practical  shop 
man  for  practical  shop  men  who  are  too  busy  to  read  theories  and  want  facts.  It.  is  the  most 
complete  all-around  book  of  its  kind  ever  published.  It  is  a  practical  book  for  practical  men, 
from  the  apprentice  in  the  shop  to  the  president  in  the  office.  It  minutely  describes  and  il- 
lustrates the  most  simple  and  yet  the  most  efficient  time  and  cost  system  yet  devised.  2nd 
Revised  and  Enlarged  Edition,  just  issued.  384  pages,  219  illustrations.  Price  .  .  .  $5.00 

FUEL 


Combustion  of  Coal  and  the  Prevention  of  Smoke.    By  WM.  M.  BARR. 

This  book  has  been  prepared  with  special  reference  to  the  generation  of  heat  by  the  com- 
bustion of  the  common  fuels  found  in  the  United  States,  and  deals  particularly  with  the  con- 
ditions necessary  to  the  economic  and  smokeless  combustion  of  bituminous  coals  in  Stationary 
and  Locomotive  Steam  Boilers. 

The  presentation  of  this 'important  subject  is  systematic  and  progressive.  The  arrangement 
of  the  book  is  in  a  series  of  practical  questions  to  which  are  appended  accurate  answers,  which 
describe  in  language,  free  from  technicalities,  the  several  processes  involved  in  the  furnace 
combustion  of  American  fuels;  it  clearly  states  the  essential  requisites  for  perfect  combustion, 
and  points  out  the  best  methods  for  furnace  construction  for  obtaining  the  greatest  quantity 
of  heat  from  any  given  quality  of  coal.  Nearly  350  pages,  fully  illustrated.  Price  .  .  $1.00 

Smoke  Prevention  and  Fuel  Economy.    By  BOOTH  and  KERSHAW. 

A  complete  treatise  for  all  interested  in  smoke  prevention  and  combustion,  being  based  on 
the  German  work  of  Ernst  Schmatolla,  but  it  is  more  than  a  mere  translation  of  the  German 
treatise,  much  being  added.  The  authors  show  as  briefly  as  possible  the  principles  of  fuel 
combustion,  the  methods  which  have  been  and  are  at  present  in  use,  as  well  as  the  proper 
scientific  methods  for  obtaining  all  the  energy  in  the  coal  and  burning  it  without  smoke. 
Considerable  space  is  also  given  to  the  examination  of  the  waste  gases,  and  several  of  the 
representative  English  and  American  mechanical  stoker  and  similar  appliances  are  described. 
The  losses  carried  away  in  the  waste  gases  are  thoroughly  analyzed  and  discussed  in  the  Ap- 
pendix, and  abstracts  are  also  here  given  of  various  patents  on  combustion  apparatus.  The 
book  is  complete  and  contains  much  of  value  to  all  who  have  charge  of  large  plants.  194  pages. 
Illustrated.  Price •  $£.5() 


18        THE     NORMAN     W.     HENLEY    PUBLISHING    CO. 

GAS  ENGINES  AND  GAS 

Gas,    Gasoline   and   Oil   Engines.     By   GARDNER   D.   Hiscox.      Revised  by 
VICTOR  W.  PAGE,  M.E. 

Just  issued  New  1918  Edition,  Revised  and  Enlarged.  Every  user  of  a  gas  engine  needs 
this  book.  Simple,  instructive  and  right  up-to-date.  The  only  complete  work  on  the  subject. 
Tells  all  about  internal  combustion  engineering,  treating  exhaustively  on  the.  design,  con- 
struction and  practical  application  of  all  forms  of  gas,  gasoline,  kerosene  and  crude  petroleum- 
oil  engines.  Describes  minutely  all  auxiliary  systems,  such  as  lubrication,  carburetion  and 
ignition.  Considers  the  theory  and  management  of  all  forms  of  explosive  motors  for  sta- 
tionary and  marine  work,  automobiles,  aeroplanes  and  motor-cycles.  Includes  also  Producer 
Gas  and  Its  Production.  Invaluable  instructions  for  all  students,  gas-engine  owners,  gas- 
engineers,  patent  experts,  designers,  mechanics,  draftsmen  arid  all  having  to  do  with  the 
modern  power.  Illustrated  by  over  400  engravings,  many  specially  made  from  engineering 
drawings,  all  in  correct  proportion.  650  pages,  435  engravings.  Price  ....  $2.50  net 

The  Gasoline  Engine  on  the  Farm:   Its  Operation,  Repair  and  Uses.    By 

XENO  W.  PUTNAM. 

This  is  a  practical  treatise  on  the  Gasoline  and  Kerosene  Engine  intended  for  the  man  who 
wants  to  know  just  how  to  manage  his  engine  and  how  to  apply  it  to  all  kinds  of  farm  work 
to  the  best  advantage. 

This  book  abounds  with  hints  and  helps  for  the  farm  and  suggestions  for  the  home  and  house- 
wife. There  is  so  much  of  value  in  this  book  that  it  is  impossible  to  adequately  describe  it 
in  such  small  space.  Suffice  to  say  that  it  is  the  kind  of  a  book  every  farmer  will  appreciate 
and  every  farm  home  ought  to  have.  Includes  selecting  the  most  suitable  engine  for  farm 
work,  its  most  convenient  and  efficient  installation,  with  chapters  on  troubles,  their  remedies, 
and  how  to  avoid  them.  The  care  and  management  of  the  farm  tractor  in  plowing,  harrowing, 
harvesting  and  road  grading  are  fully  covered;  also  plain  directions  are  given  for  handling 
the  tractor  on  the  road.  Special  attention  is  given  to  relieving  farm  life  of  its  drudgery  by 
applying  power  to  the  disagreeable  small  tasks  which  must  otherwise  be  done  by  hand.  Many 
home-made  contrivances  for  cutting  wood,  supplying  kitchen,  garden,  and  barn  with  water, 
loading,  hauling  and  unloading  hay,  delivering  grain  to  the  bins  or  the  feed  trough  are  in- 
cluded; also  full  directions  for  making  the  engine  milk  the  cows,  churn,  wash,  sweep  the 
house  and  clean  the  windows,  etc.  Very  fully  illustrated  with  drawings  of  working  parts  and 
cuts  snowing  Stationary,  Portable  and  Tractor  Engines  doing  all  kinds  of  farm  work.  All 
money-making  farms  utilize  power.  Learn  how  to  utilize  power  by  reading  the  pages  of  this 
book.  It  is  an  aid  to  the  result  getter,  invaluable  to  the  up-to-date  farmer,  student,  black- 
smith, implement  dealer  and,  in  fact,  all  who  can  apply  practical  knowledge  of  stationary 
gasoline  engines  or  gas  tractors  to  advantage.  530  pages.  Nearly  180  engravings.  Price  $2.00 

WHAT  IS  SAID  OF  THIS  BOOK: 

"Am  much  pleased  with  the  book  and  find  it  to  be  very  complete  and  up-to-date.  I  will 
heartily  recommend  it  to  students  and  farmers  whom  I  think  would  stand  in  need  of  such  a 
work,  as  I  think  it  is  an  exceptionally  good  one." — N.  S.  Gardiner,  Prof,  in  Charge,  Clemson 
Agr.  College  of  S.  C.;  Dept.  of  Agri.  and  Agri.  Exp.  Station,  Clemson  College,  S.  C. 
"I  feel  that  Mr.  Putnam's  book  covers  the  main  points  which  a  farmer  should  know." — R.  T. 
Burdick,  Instructor  in  Agronomy,  University  of  Vermont,  Burlington,  Vt. 

Gasoline  Engines:  Their  Operation,  Use  and  Care.    By  A.  HYATT  VERRILL. 

The  simplest,  latest  and  most  comprehensive  popular  work  published  on  Gasoline  Engines, 
describing  what  the  Gasoline  Engine  is;  its  construction  and  operation;  how  to  install  it; 
how  to  select  it;  how  to  use  it  and  how  to  remedy  troubles  encountered.  Intended  for  Owners, 
Operators  and  Users  of  Gasoline  Motors  of  all  kinds.  This  work  fully  describes  and  illustrates  the 
various  types  of  Gasoline  Engines  used  in  Motor  Boats,  Motor  Vehicles  and  Stationary  Work. 
The  parts,  accessories  and  appliances  are  described  with  chapters  on  ignition,  fuel,  lubrication, 
operation  and  engine  troubles.  Special  attention  is  given  to  the  care,  operation  and  repair 
of  motors,  with  useful  hints  and  suggestions  on  emergency  repairs  and  makeshifts.  A  com- 
plete glossary  of  technical  terms  and  an  alphabetically  arranged  table  of  troubles  and  their 
symptoms  form  most  valuable  and  unique  features  of  this  manual.  Nearly  every  illustration 
in  the  book  is  original,  having  been  made  by  the  author.  Every  page  is  full  of  interest  and 
value.  A  book  which  you  cannot  afford  to  be  without.  275  pages,  152  specially  made 
engravings.  Price  .  . $1.50 

Gas  Engine  Construction,  or  How  to  Build  a  Half-horsepower  Gas  Engine. 

By  PARSELL  and  WEED. 

A  practical  treatise  of  300  pages  describing  the  theory  and  principles  of  the  action  of  Gas 
Engines  of  various  types  and  the  design  and  construction  of  a  half-horsepower  Gas  Engine, 
with  illustrations  of  the  work  in  actual  progress,  together  with  the  dimensioned  working  draw- 
ings, giving  clearly  the  sizes  of  the  various  details;  for  the  student,  the  scientific  investigator, 
and  the  amateur  mechanic.  This  book  treats  of  the  subject  more  from  the  standpoint  of 
practice  than  that  of  theory.  The  principles  of  operation  of  Gas  Engines  are  clearly  and 
simply  described,  and  then  the  actual  construction  of  a  half-horsepower  engine  is  taken  up, 
step  by  step,  showing  in  detail  the  making  of  the  Gas  Engine.  3rd  Edition.  300  pages. 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    19 


How  to  Run  and  Install  Two-  and  Four-Cycle  Marine  Gasoline  Engines. 

By  C.  VON  CULIN. 

Revised  and  enlarged  edition  just  issued.  The  object  of  this  little  book  is  to  furnish  a  pocket 
instructor  for  the  beginner,  the  busy  man  who  uses  an  engine  for  pleasure  or  profit,  but  who 
does  not  have  the  time  or  inclination  for  a  technical  book,  but  simply  to  thoroughly  under- 
stand how  to  properly  operate,  install  and  care  for  his  own  engine.  The  index  refers  to  each 
trouble,  remedy,  and  subject  alphabetically.  Being  a  quick  reference  to  find  the  cause,  remedy 
and  prevention  for  troubles,  and  to  become  an  expert  with  his  own  engine.  Pocket  size. 
Paper  binding.  Price 25  CCIltS 

Modern  Gas  Engines  and  Producer  Gas  Plants.    By  R.  E.  MATHOT. 

A  guide  for  the  gas  engine  designer,  user,  and  engineer  in  the  construction,  selection,  purchase, 
installation,  operation,  and  maintenance  of  gas  engines.  More  than  one  book  on  gas  engines 
has  been  written,  but  not  one  has  thus  far  even  encroached  on  the  field  covered  by  this  book. 
Above  all,  Mr.  Mathot's  work  is  a  practical  guide.  Recognizing  the  need  of  a  volume  that 
would  assist  the  gas  engine  user  in  understanding  thoroughly  the  motor  upon  which  he  depends 
for  power,  the  author  has  discussed  his  subject  without  the  help  of  any  mathematics  and  with- 
out elaborate  theoretical  explanations.  Every  part  of  the  gas  engine  is  described  in  detail, 
tersely,  clearly,  with  a  thorough  understanding  of  the  requirements  of  the  mechanic.  Help- 
ful suggestions  as  to  the  purchase  of  an  engine,  its  installation,  care,  and  operation,  form  a 
most  valuable  feature  of  the  work.  320  pages,  175  detailed  illustrations.  Price  .  .  .  $2. 50 

The  Modern  Gas  Tractor.    By  VICTOR  W.  PAGE,  M.E. 

A  complete  treatise  describing  all  types  and  sizes  of  gasoline,  kerosene  and  oil  tractors.  Con- 
siders design  and  construction  exhaustively,  gives  complete  instructions  for  care,  operation  and 
repair,  outlines  all  practical  applications  on  the  road  and  in  the  field.  The  best  and  latest 
work  on  farm  tractors  and  tractor  power  plants.  A  work  needed  by  farmers,  students,  black- 
smiths, mechanics,  salesmen,  implement  dealers,  designers  and  engineers.  2nd  Edition,  Re- 
vised. 504  pages,  228  illustrations,  3  folding  plates.  Price $2.00 

GEARING  AND  CAMS 

Bevel  Gear  Tables.    By  D.  AG.  ENGSTROM. 

A  book  that  will  at  once  commend  itself  to  mechanics  and  draftsmen.  Does  away  with  all 
the  trigonometry  and  fancy  figuring  on  bevel  gears,  and  makes  it  easy  for  anyone  to  lay  them 
out  or  make  them  just  right.  There  are  36  full-page  tables  that  show  every  necessary  dimen- 
sion for  all  sizes  or  combinations  you're  apt  to  need.  No  puzzling,  figuring  or  guessing.  Gives 
placing  distance,  all  the  angles  (including  cutting  angles),  and  the  correct  cutter  to  use.  A 
copy  of  this  prepares  you  for  anything  in  the  bevel-gear  line.  3rd  Edition.  66  pages. 
Price $1.00 

Change  Gear  Devices.    By  OSCAR  E.  PERRIGO. 

A  practical  book  for  every  designer,  draftsman,  and  mechanic  interested  in  the  invention  and 
development  of  the  devices  for  feed  changes  on  the  different  machines  requiring  such  mechanism. 
All  the  necessary  information  on  this  subject  is  taken  up,  analyzed,  classified,  sifted,  and  con- 
centrated for  the  use  of  busy  men  who  have  not  the  time  to  go  through  the  masses  of  irrelevant 
matter  with  which  such  a  subject  is  usually  encumbered  and  select  such  information  as  will 
be  useful  to  them. 

It  shows  just  what  has  been  done,  how  it  has  been  done,  when  it  was  done,  and  who  did  it. 
It  saves  time  in  hunting  up  patent  records  and  re-inventing  old  ideas.  88  pages.  3rd  Edition, 
^ice $1.00 

Drafting  of  Cams.    By  Louis  ROTTILLION. 

The  laying  out  of  cams  is  a  serious  problem  unless  you  know  how  to  go  at  it  right.  This  puts 
you  on  the  right  road  for  practically  any  kind  of  cam  you  are  likely  to  run  up  against.  3rd 
Edition.  Price 35  (Tilts 

HYDRAULICS 

Hydraulic  Engineering.    By  GARDNER  D.  Hiscox. 

A  treatise  on  the  properties,  power,  and  resources  of  water  for  all  purposes.  Including  the 
measurement  of  streams,  the  flow  of  water  in  pipes  or  conduits;  the  horsepower  of  falling  water, 
turbine  and  impact  water-wheels,  wave  motors,  centrifugal,  reciprocating  and  air-lift  pumps. 
With  300  figures  and  diagrams  and  36  practical  tables.  All  who  are  interested  in  water-works 
development  will  find  this  book  a  useful  one,  because  it  is  an  entirely  practical  treatise  upon 
a  subject  of  present  importance  and  cannot  fail  in  having  a  far-reaching  influence,  and  for  this 
reason  should  have  a  place  in  the  working  library  of  every  engineer.  Among  the  subjects 
treated  are:  Historical  Hydraulics;  Properties  of  Water;  Measurement  of  the  Flow  of  Streams; 


23        THE     NORMAN    W.    HENLEY    PUBLISHING     CO. 

Flow  from  Sub-surface  Orifices  and  Nozzles;  Flow  of  Water  in  Pipes;  Siphons  of  Various 
Kinds;  Dams  and  Great  Storage  Reservoirs;  City  and  Town  Water  Supply;  Wells  and  Their 
Reinforcement;  -Air-lift  Methods  of  Raising  Water;  Artesian  Wells;  Irrigation  of  Arid  Dis- 
tricts; Water  Power;  Water  Wheels;  Pumps  and  Pumping  Machinery;  Reciprocating  Pumps; 
Hydraulic  Power  Transmission;  Hydraulic  Mining;  Canals;  Ditches;  Conduits  and  Pipe 
Lines;  Marine  Hydraulics;  Tidal  and  Sea  Wave  Power,  etc.  320  pages.  Price  .  .  .  $4.00 

ICE  AND  REFRIGERATION 

Pocketbook  of  Refrigeration  and  Ice  Making.    By  A.  J.  WALLIS-TAYLOR. 

This  is  one  of  the  latest  and  most  comprehensive  reference  books  published  on  the  subject  of 
refrigeration  and  cold  storage.  It  explains  the  properties  and  refrigerating  effect  of  the  dif- 
ferent fluids  in  use,  the  management  of  refrigerating  machinery  and  the  construction  and  insu- 
lation of  cold  rooms  with  their  required  pipe  surface  for  different  degrees  of  cold;  freezing 
mixtures  and  non-freezing  brines,  temperatures  of  cold  rooms  for  all  kinds  of  provisions,  cold 
storage  charges  for  all  classes  of  goods,  ice  making  and  storage  of  ice,  data  and  memoranda 
for  constant  reference  by  refrigerating  engineers,  with  nearly  one  hundred  tables  containing 
valuable  references  to  every  fact  and  condition  required  in  the  installment  and  operation  of  a 
refrigerating  plant.  New  edition  just  published.  Price $1.50 

INVENTIONS— PATENTS 

Inventors'  Manual:   How  to  Make  a  Patent  Pay. 

This  is  a  book  designed  as  a  guide  to  inventors  in  perfecting  their  inventions,  taking  out  their 
patents  and  disposing  of  them.  It  is  not  in  any  sense  a  Patent  Solicitor's  Circular  nor  a  Patent 
Broker's  Advertisement.  No  advertisements  of  any  description  appear  in  the  work.  It  is  a 
book  •  containing  a  quarter  of  a  century's  experience  of  a  successful  inventor,  together  with 
notes  based  upon  the  experience  of  many  other  inventors. 

Among  the  subjects  treated  in  this  work  are:  How  to  Invent.  How  to  Secure  a  Good  Patent. 
Value  of  Good  Invention.  How  to  Exhibit  an  Invention.  How  to  Interest  Capital.  How 
to  Estimate  the  Value  of  a  Patent.  Value  of  Design  Patents.  Value  of  Foreign  Patents. 
Value  of  Small  inventions.  Advice  on  Selling  Patents.  Advice  on  the  Formation  of  Stock 
Companies.  Advice  on  the  Formation  of  Limited  Liability  Companies.  Advice  on  Disposing 
of  Old  Patents.  Advice  as  to  Patent  Attorneys.  Advice  as  to  Selling  Agents.  Forms  of 
Assignments.  License  and  Contracts.  State  Laws  Concerning  Patent  Rights.  1900  Census 
of  the  United  States  by  Counts  of  Over  10,000  Population.  Revised  Edition.  120  pages. 
Price $1.00 

KNOTS 


Knots,  Splices  and  Rope  Work.    By  A.  HYATT  VERRILL. 

This  is  a  practical  book  giving  complete  and  simple  directions  for  making  all  the  most  useful 
and  ornamental  knots  in  common  use,  with  chapters  on  Splicing,  Pointing,  Seizing,  Serving, 
etc.  This  book  is  fully  illustrated  with  154  original  engravings,  which  show  how  each  knot, 
tie  or  splice  is  formed,  and  its  appearance  when  finished.  The  book  will  be  found  of  the  greatest 
value  to  Campers,  Yachtsmen,  Travelers,  Boy  Scouts,  in  fact,  to  anyone  having  occasion  to 
use  or  handle  rope  or  knots  for  any  purpose.  The  book  is  thoroughly  reliable  and  practical, 
and  is  not  only  a  guide,  but  a  teacher.  It  is  the  standard  work  on  the  subject.  Among  the 
contents  are:  1.  Cordage,  Kinds  of  Rope.  Construction  of  Rope,  Parts  of  Rope  Cable  and 
Bolt  Rope.  Strength  of  Rope,  Weight  of  Rope.  2.  Simple  Knots  and  Bends.  Terms  Used 
in  Handling  Rope.  Seizing  Rope.  3.  Ties  and  Hitches.  4.  Noose,  Loops  and  Mooring 
Knots.  5.  Shortenings,  Grommets  and  Salvages.  6.  Lashings,  Seizings  and  Splices.  7. 
Fancy  Knots  and  Rope  Work.  128  pages,  150  original  engravings.  2nd  Revised  Edition. 

Price  . 75  cents 

LATHE  WORK 

Lathe  Design,  Construction,  and  Operation,  with  Practical  Examples  of 
Lathe  Work.     By  OSCAR  E.  PERRIGO. 

A  new,  revised  edition,  and  the  only  complete  American  work  on  the  subject,  written  by  a 
man  who  knows  not  only  how  work  ought  to  be  done,  but  who  also  knows  how  to  do  it,  and 
how  to  convey  this  knowledge  to  others.  It  is  strictly  up-to-date  in  its  descriptions  and 
illustrations.  Lathe  history  and  the  relations  of  the  lathe  to  manufacturing  are  given; 
also  a  description  of  the  various  devices  for  feeds  and  thread-cutting  mechanisms  from  early 
efforts  in  this  direction  to  the  present  time.  Lathe  design  is  thoroughly  discussed,  includ- 
ing back  gearing,  driving  cones,  thread-cutting  gears,  and  all  the  essential  elements  of  the 
modern  lathe.  The  classification  of  lathes  is  taken  up,  giving  the  essential  differences  of 
the  several  types  of  lathes  including,  as  is  usually  understood,  engine  lathes,  bench  lathes, 
speed  lathes,  forge  lathes,  gap  lathes,  pulley  lathes,  forming  lathes,  multiple-spindle  lathes, 
rapid-reduction  lathes,  precision  lathes,  turret  lathes,  special  lathes,  electrically  driven  lathes, 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    21 

etc.  In  addition  to  the  complete  exposition  on  construction  and  design,  much  practical 
matter  on  lathe  installation,  care  and  operation  has  been  incorporated  in  the  enlarged  new- 
edition.  All  kinds  of  lathe  attachments  for  drilling,  milling,  etc.,  are  described  and  com- 
plete instructions  are  given  to  enable  the  novice  machinist  to  grasp  the  art  of  lathe  operation 
as  well  as  the  principles  involved  in  design.  A  number  of  difficult  machining  operations 
are  described  at  length  and  illustrated.  The  new  edition  has  nearly  500  pages  and  350  illus- 
trations. Price $2.50 

WHAT  IS  SAID  OF  THIS  BOOK: 

"This  is  a  lathe  book  from  beginning  to  end,  and  is  just  the  kind  of  a  bo9k  which  one  de- 
lights to  consult — a  masterly  treatment  of  the  subject  in  hand." — Engineering  News. 
"This  work  will  be  of  exceptional  interest  to  any  one  who  is  interested  in  lathe  practice,  as 
one  very  seldom  sees  such  a  complete  treatise  on  a  subject  as  this  is  on  the  lathe." — Cana- 
dian Machinery. 

•+* 

Practical  Metal  Turning.     By  JOSEPH  G.  HORNEB. 

A  work  of  404  pages,  fully  illustrated,  covering  in  a  comprehensive  manner  the  modern  prac- 
tice of  machining  metal  parts  in  the  lathe,  including  the  regular  engine  lathe,  its  essential 
design,  its  uses,  its  tools,  its  attachments,  and  the  manner  of  holding  the  work  and  perform- 
ing the  operations.  The  modernized  engine  lathe,  its  methods,  tools  and  great  range  of  accu- 
rate work.  The  turret  lathe,  its  tools,  accessories  and  methods  of  performing  its  functions. 
Chapters  on  special  work,  grinding,  tool  holders,  speeds,  feeds,  modern  tool  steels,  etc. 
Second  edition ' $3.50 

Turning  and  Boring  Tapers.    By  FRED  H.  COLVIN. 

There  are  two  ways  to  turn  tapers;  the  right  way  and  one  other.  This  treatise  has  to  do 
with  the  right  way;  it  tells  you  how  to  start  the  work  properly,  how  to  set  the  lathe,  what 
tools  to  use  and  how  to  use  them,  and  forty  and  one  other  little  things  that  you  should  know. 
Fourth  edition •  •  •  25  CClltS 

LIQUID  AIR 

Liquid  Air  and  the  Liquefaction  of  Gases.    By  T.  O'CONOR  SLOANE. 

This  book  gives  the  history  of  the  theory,  discovery  and  manufacture  of  Liquid  Air,  arid. 

contains  an  illustrated  description  of  all  the  experiments  that  have  excited  the  wonder  of 

audiences  all  over  the  country.      It  shows  how  liquid  air,  like  water,  is  carried  hundreds  of 

miles  and  is  handled  in  open  buckets.      It  tells  what  may  be  expected  from  it  in  the  near 

future. 

A  book  that  renders  simple  one  of  the  most  perplexing  chemical  problems  of  the  century. 

Startling  developments  illustrated  by  actual  experiments. 

It  is  not  only  a  work  of  scientific  interest  and  authority,  but  is  intended  for  the  general  reader, 

being  written  in  a  popular  style — easily  understood  by  every  one.      Second  edition.     365- 

pages.     Price $2.00 

LOCOMOTIVE  ENGINEERING 

Air-Brake  Catechism.     By  ROBERT  H.  BLACKALL. 

This  book  is  a  standard  text-book.  It  covers  the  Westinghouse  Air-Brake  Equipment, 
including  the  No.  5  and  the  No.  6  E.-T.  Locomotive  Brake  Equipment;  the  K  (Quick  Ser- 
vice) Triple  Valve  for  Freight  Service;  and  the  Cross-Compound  Pump.  The  operation  of 
all  parts  of  the  apparatus  is  explained  in  detail,  and  a  practical  way  of  finding  their  pecu- 
liarities and  defects,  with  a  proper  remedy,  is  given.  It  contains  2,000  questions  with  their 
answers,  which  will  enable  any  railroad  man  to  pass  any  examination  on  the  .subject  of 
Air  Brakes.  Endorsed  and  used  by  air-brake  instructors  and  examiners  9n.  nearly  every 
railroad  in  the  United  States.  Twenty-sixth  edition.  411  pages,  fully  illustrated  with 
colored  plates  and  diagrams.  Price $2.00 

American  Compound  Locomotives.     By  FRED  H.  COLVIN. 

The  only  book  on  compounds  for  the  engineman  or  shopman  that  shows  in  a  plain,  prac- 
tical way  the  various  features  of  compound  locomotives  in  use.  Shows  how  they  are  made, 
what  to  do  when  they  break  down  or  balk.  Contains  sections  as  follows:  A  Bit  of  History. 
Theory  of  Compounding  Steam  Cylinders.  Baldwin  Two-Cylinder  Compound.  Pittsburgh 
Two-Cylinder  Compound.  Rhose  Island  Compound.  Richmond  Compound.  Rogers  Com- 
pound. Schenectady  Two-Cylinder  Compound.  Vauclain  Compound.  Tandem  Compounds. 
Baldwin  Tandem.  The  Colvin-Wightman  Tandem.  Scbenectady  Tandem.  Balanced 
Locomotives.  Baldwin  Balanced  Compound.  Plans  for  Balancing.  Locating  Blows. 
Breakdowns.  Reducing  Valves.  Drifting.  Valve  Motion.  Disconnecting.  Power  of  Com- 
pound Locomotives.  Practical  Notes. 

Fully  illustrated  and  containing  ten  special  "Duotone"  inserts  on  heavy  Plate  Paper,  show- 
ing different  types  of  Compounds.  142  pages.  Price .....  .  $1.00 


22        THE     NORMAN    W.     HENLEY    PUBLISHING     CO. 

Application  of  Highly  Superheated  Steam  to  Locomotives.  By  ROBERT 
GARBE. 

A  practical  book  which  cannot  be  recommended  too  highly  to  those  motive-power  men  who 
are  anxious  to  maintain  the  highest  efficiency  in  their  locomotives.  Contains  special  chap- 
ters on  Generation  of  Highly  Superheated  Steam;  Superheated  Steam  and  the  Two-Cylinder 
Simple  Engine;  Compounding  and  Superheating;  Designs  of  Locomotive  Superheaters; 
Constructive  Details  of  Locomotives  Using  Highly  Superheated  Steam.  Experimental  and 
Working  Results.  Illustrated  with  folding  plates  and  tables.  Cloth.  Price  ....  $3.50 

Combustion  of  Coal  and  the  Prevention  of  Smoke.    By  WM.  M.  BARR. 

This  book  has  been  prepared  with  special  reference  to  the  generation  of  heat  by  the  com- 
bustion of  the  common  fuels  found  in  the  United  States  and  deals  particularly  with  the 
conditions-  necessary  to  the  economic  and  smokeless  combustion  of  bituminous  coal  in  Sta- 
tionary and  Locomotive  Steam  Boilers. 

Presentation  of  this  important  subject  is  systematic  and  progressive.  The  arrangement  of 
the  book  is  in  a  series  of  practical  questions  to  which  are  appended  accurate  answers,  which 
describe  in  language  free  from  technicalities  the  several  processes  involved  in  the  furnace 
combustion  of  American  fuels;  it  clearly  states  the  essential  requisites  for  perfect  combus- 
tion, and  points  out  the  best  methods  of  furnace  construction  for  obtaining  the  greatest 
quantity  of  heat  from  any  given  quality  of  coal.  Nearly  350  pages,  fully  illustrated. 
Price $1.00 

Diary  of  a  Round-House  Foreman.    By  T.  S.  REILLY. 

This  is  the  greatest  book  of  railroad  experiences  ever  published.  Containing  a  fund  of  in- 
formation and  suggestions  along  the  line  of  handling  men,  organizing,  etc.,  that  one  cannot 
afford  to  miss.  •  176  pages.  Price §1 .00 

Link  Motions,  Valves  and  Valve  Setting.  By  FRED  H.  COLVIN,  Associate  Editor 
of  "American  Machinist." 

A  handy  book  for  the  engineer  or  machinist  that  clears  up  the  mysteries  of  valve  setting. 
Shows  the  different  valve  gears  in  use,  how  they  work,  and  why.  Piston  and  slide  valves 
of  different  types  are  illustrated  and  explained.  A  book  that  every  railroad  man  in  the 
motive-power  department  ought  to  have.  Contains  chapters  on  Locomotive  Link  Motion, 
Valve  Movements,  Setting  Slide  Valves,  Analysis  by  Diagrams,  Modern  Practice,  Slip  of 
Block  Slice  Valves,  Piston  Valves,  Setting  Piston  Valves,  Joy-Allen  Valve  Gear,  Walschaert 
Valve  Gear,  Gooch  Valve  Gear,  Alfree-Hubbell  Valve  Gear,  etc.,  etc.  Fully  illustrated. 

Price 50  cents 

Locomotive  Boiler  Construction.     By  FRANK  A.  KLEINHANS. 

The  construction  of  boilers  in  general  is  treated  and,  following  this,  the  locomotive  boiler 
is  taken  up  in  the  order  in  which  its  various  parts  go  through  the  shop.  Shows  all  types 
of  boilers  used;  gives  details  of  construction;  practical  facts,  such  as  life  of  riveting,  punches 
and  dies;  work  done  per  day,  allowance  for  bending  and  flanging  sheets  and  other  data. 
Including  the  recent  Locomotive  Boiler  .Inspection  Laws  and  Examination  Questions  with 
their  answers  for  Government  Inspectors.  Contains  chapters  on  Laying-Out  Work;  Flang- 
ing and  Forging;  Punching;  Shearing;  Plate  Planing;  General  Tables;  Finishing  Parts; 
Bending;  Machinery  Parts;  Riveting;  Boiler  Details;  Smoke-Box  Details;  Assembling 
and  Calking;  Boiler-Shop  Machinery,  etc.,  etc. 

There  isn't  a  man  who  has  anything  to  do  with  boiler  work,  either  new  or  repair  work,  who 
doesn't  need  this  book.  The  manufacturer,  superintendent,  foreman  and  boiler  worker — 
all  need  it.  No  matter  what  the  type  of  bioler,  you'll  find  a  mint  of  information  that  you 
wouldn't  be  without.  Over  400  pages,  five  large  folding  plates.  Price $3.00 

Locomotive  Breakdowns  and  their  Remedies.  By  GEO.  L.  FOWLER.  Re- 
vised by  WM.  W.  WOOD,  Air-Brake  Instructor.  Just  issued.  Revised  pocket 
edition. 

It  is  out  of  the  question  to  try  and  tell  you  about  every  subject  that  is  covered  in  this  pocket 
edition  of  Locomotive  Breakdowns.  Just  imagine  all  the  common  troubles  that  an  engineer 
may  expect  to  happen  some  time,  and  then  add  all  of  the  unexpected  ones,  troubles  that  could 
occur,  but  that  you  have  never  thought  about,  and  you  will  find  that  they  are  all  treated  with 
the  very  best  methods  of  repair.  Walschaert  Locomotive  Valve  Gear  Troubles,  Electric 
Headlight  Troubles,  as  well  as  Questions  and  Answers  on  the  Air  Brake  are  all  included.  312 
pages.  8th  Revised  Edition.  Fully  illustrated.  Price $1.00 

Locomotive  Catechism.     By  ROBERT  GRIMSHAW. 

The  revised  edition  of  "Locomotive  Catechism,"  by  Robert  Grimshaw,  is  a  New  Book  from 
Cover  to  C9yer.  It  contains  twice  as  many  pages  and  double  the  number  of  illustrations  of 
previous  editions.  Includes  the  greatest  amount  of  practical  information  ever  published  on 
the  construction  and  management  of  modern  locomotives.  Specially  Prepared  Chapters  on 
the  Walschaert  Locomotive  Valve  Gear,  the  Air-Brake  Equipment  and  the  Electric  Headlight 
are  given. 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    23 

It  commends  itself  at  once  to  every  Engineer  and  Fireman,  and  to  all  who  are  going  in  for 
examination  or  promotion.  In  plain  language,  with  full,  complete  answers,  not  only  all  the 
questions  asked  by  the  examining  engineer  are  given,  but  those  which  the  young  and  less 
experienced  would  ask  the  veteran,  and  which  old  hands  ask  as  "stickers."  It  is  a  veritable 
Encyclopedia  of  the  Locomotive,  is  entirely  free  from  mathematics,  easily  understood  and 
thoroughly  up  to  date.  Contains  over  4,000  Examination  Questions  with  their  Answe 
825  pages,  437  illustrations,  and  3  folding  plates.  28th  Revised  Edition.  Price 

Practical  Instructor  and  Reference  Book  for  Locomotive  Firemen  and 
Engineers.     By  CHAS.  F.  LOCKHART. 

An  entirely  new  book  on  the  Locomotive.  It  appeals  to  every  railroad  man,  as  it  tells  him 
how  tilings  are  done  and  the  right  way  to  do  them.  Written  by  a  man  who  has  had  years  of 
practical  experience  in  locomotive  shops  and  on  the  road  firing  and  running.  The  information 
given  in  this  book  cannot  be  found  in  any  other  similar  treatise.  Eight  hundred  and  fifty-one 
questions  with  their  answers  are  included,  which  will  prove  specially  helpful  to  those  preparing 
for  examination.  Practical  information  on:  The  Construction  and  Operation  of  Locomotives, 
Breakdowns  and  their  Remedies,  Air  Brakes  and  Valve  Gears.  Rules  and  Signals  are  handled 
in  a  thorough  manner.  As  a  book  of  reference  it  cannot  be  excelled.  The  book  is  divided 
in  to  six  parts,  as  follows:  1.  The  Fireman's  Duties.  2.  General  Description  of  the  Locomotive. 
3.  Breakdowns  and  their  Remedies.  4.  Air  Brakes.  5.  Extracts  from  Standard  Rules. 
6.  Questions  for  Examination.  The  851  questions  have  been  carefully  selected  and  arranged. 
These  cover  the  examinations  required  by  the  different  railroads.  368  pages,  83  illustrations. 
Price $1.50 

Prevention  of  Railroad  Accidents^  or  Safety  in  Railroading.    By  GEORGE 
BRADSHAW. 

This  book  is  a  heart-to-heart  talk  with  Railroad  Employees,  dealing  with  facts,  not  theories, 
and  showing  the  men  in  the  ranks,  from  every-day  experience,  how  accidents  occur  and  how 
they  may  be  avoided.  The  book  is  illustrated  with  seventy  original  photographs  and  drawings 
showing  the  safe  and  unsafe  methods  of  work.  No  visionary  schemes,  no  ideal  pictures. 
Just  Plain  Facts  and  Practical  Suggestions  are  given.  Every  railroad  employee  who  reads  the 
book  is  a  better  and  safer  man  to  have  in  railroad  service.  It  gives  just  the  information  which 
will  be  the  means  of  preventing  many  injuries  and  deaths.  All  railroad  employees  should 
procure  a  copy,  read  it,  and  do  their  part  in  preventing  accidents.  169  pages.  Pocket  size. 
Fully  illustrated.  Price 50  cents 

Train  Rule  Examinations  Made  Easy.    By  G.  E.  COLLINQWOOD. 

This  is  the  only  practical  work  on  train  rules  in  print.  Every  detail  is  covered,  and  puzzling 
points  are  explained  in  simple,  comprehensive  language,  making  it  a  practical  treatise  for  the 
Train  Dispatcher,  Engineman,  Trainman,  and  all  others  who  have  to  do  with  the  movements 
of  trains.  Contains  complete  and  reliable  information  of  the  Standard  Code  of  Train  Rules 
for  single  track.  Shows  Signals  in  Colors,  as  used  on  the  different  roads.  Explains  fully  the 
practical  application  of  train  orders,  giving  a  clear  and  definite  understanding  of  all  orders 
which  may  be  used.  The  meaning  and  necessity  for  certain  rules  are  explained  in  such  a 
manner  that  the  student  may  know  beyond  a  doubt  the  rights  conferred  under  any  orders  he 
may  receive  or  the  action  required  by  certain  rules.  As  nearly  all  roads  require  trainmen  to 
pass  regular  examinations,  a  complete  set  of  examination  questions,  with  their  answers,  are 
included.  These  will  enable  the  student  to  pass  the  required  examinations  with  credit  to 
himself  and  the  road  for  which  he  works.  2nd  Edition,  Revised.  256  pages,  fully  illustrated, 
with  Train  Signals  in  Colors.  Price $1.25 

The  Walschaert  and  Other  Modern  Radial  Valve  Gears  for  Locomotives. 

By  WM.  W.  WOOD. 

If  you  would  thoroughly  understand  the  Walschaert  Valve  Gear  you  should  possess  a  copy 
of  this  book,  as  the  author  takes  the  plainest  form  9f  a  steam  engine — a  stationary  engine  in 
the  rough,  that  will  only  turn  its  crank  in  one  direction — and  from  it  builds  up,  with  the  read- 
er's help,  a  modern  locomotive  equipped  with  the  Walschaert  Valve  Gear,  complete.  The 
points  discussed  are  clearly  illustrated:  Two  large  folding  plates  that  show  the  positions  of 
the  valves  of  both  inside  or  outside  admission  type,  as  well  as  the  links  and  other  parts  of  the 
gear  when  the  crank  is  at  nine  different  points  in  its  revolution,  are  especially  valuable  in  mak- 
ing the  movement  clear.  These  employ  sliding  cardboard  models  which  are  contained  in  a 
pocket  in  the  cover. 

The  book  is  divided  into  five  general  divisions,  as  follows:  1.  Analysis  of  the  gear.  2.  De- 
signing and  erecting  the  gear.  3.  Advantages  of  the  gear.  4.  Questions  and  answers  relating 
to  the  Walschaert  Valve  Gear.  5.  Setting  valves  with  the  Walschaert  Valve  Gear;  the  three 
primary  types  of  locomotive  valve  motion;  modern  radial  valve  gears  other  than  the  Wal- 
schaert ;  the  Hobart  All-free  Valve  and  Valve  Gear,  with  questions  and  answers  on  breakdowns: 
the  Baker-Pilliod  Valve  Gear;  the  Improved  Baker-Pilliod  Valve  Gear,  with  questions  and 
answers  on  breakdowns. 

The  questions  with  full  answers  given  will  be  especially  valuable  to  firemen  and  engineers  in 
preparing  for  an  examination  for  promotion.  245  pages.  3rd  Revised  Edition.  Price  $1.50 


24        THE     NORMAN    W.     HENLEY     PUBLISHING     CO. 

Westinghouse  E-T  Air-Brake  Instruction  Pocket  Book.     By  WM.  W.  WOOD, 
Air-Brake  Instructor. 

Here  is  a  book  for  the  railroad  man,  and  the  man  who  aims  to  be  one.  It  is  without  doubt 
the  only  complete  work  published  on  the  Westinghouse  E-T  Locomotive  Brake  Equipment. 
Written  by  an  Air-Brake  Instructor  who  knows  just  what  is  needed.  It  covers  the  subject 
thoroughly.  Everything  about  the  New  Westinghouse  Engine  and  Tender  Brake  Equip- 
ment, including  the  standard  No.  5  and  the  Perfected  No.  6  style  of  brake,  is  treated  in  detail. 
Written  in  plain  English  and  profusely  illustrated  with  Colored  Plates,  which  enable  one  to 
trace  the  flow  of  pressures  throughout  the  entire  equipment.  The  best  book  ever  published 
on  the  Air  Brake.  Equally  good  for  the  beginner  and  the  advanced  engineer.  Will  pass  any 
one  through  any  examination.  It  informs  and  enlightens  you  on  every  point.  Indispensable 
to  every  enginernan  and  trainman. 

Contains  examination  questions  and  answers  on  the  E-T  equipment.  Covering  what  the  E-T 
Brake  is.  How  it  should  be  operated.  What  to  do  when  defective.  Not  a  question  can  be 
asked  of  the  engineman  up  for  promotion,  on  either  the  No.  5  or  the  No.  6  E-T  equipment, 
that  is  not  asked  and  answered  in  the  book.  If  you  want  to  thoroughly  understand  the  E-T 
equipment  get  a  copy  of  this  book.  It  covers  every  detail.  Makes- Air-Brake  troubles  and 
examinations  easy.  Price $1.50 

MACHINE-SHOP  PRACTICE 

American  Tool  Making  and  Interchangeable  Manufacturing.    By  J.  V. 

WOODWORTH. 

A  "shoppy"  book,  containing  no  theorizing,  n'o  problematical  or  experimental  devices.  There 
are  no  badly  proportioned  and  impossible  diagrams,  no  catalogue  cuts,  but  a  valuable  collec- 
tion of  drawings  and  descriptions  of  devices,  the  rich  fruits  of  the  author's  own  experience. 
In  its  500-odd  pages  the  one  subject  only,  Tool  Making,  and  whatever  relates  thereto,  is  dealt 
with.  The  work  stands  without  a  rival.  It  is  a  complete,  practical  treatise,  on  the  art  of 
American  Tool  Making  and  system  of  interchangeable  manufacturing  as  carried  on  to-day  in 
the  United  States.  In  it  are  described  and  illustrated  all  of  the  different  types  and  classes  of 
small  tools,  fixtures,  devices,  and  special  appliances  which  are  in  general  use  in  all  machine- 
manufacturing  and  metal-working  establishments  where  economy,  capacity,  and  interchange- 
ability  in  the  production  of  machined  metal  parts  are  imperative.  The  science  of  jig  making 
is  exhaustively  discussed,  and  particular  attention  is  paid  to  drill  jigs,  boring,  profiling  arid 
milling  fixtures  and  other  devices  in  which  the  parts  to  be  machined  are  located  and  fastened 
within  the  contrivances.  All  of  the  tools,  fixtures,  and  devices  illustrated  and  described  have 
been  or  are  used  for  the  actual  production  of  work,  such  as  parts  of  drill  presses,  lathes,  patented 
machinery,  typewriters,  electrical  apparatus,  mechanical  appliances,  "brass  goods,  composition 
parts,  mould  products,  sheet-metal  articles,  drop-forgings,  jewelry,  watches,  medals,  coins,  etc. 
531  pages.  Price $4.00 

HENLEY'S  ENCYCLOPEDIA  OF  PRACTICAL  ENGINEERING  AND  ALLIED 
TRADES.    EDITED  by  JOSEPH  G.  HORNER,  A.M.I.,  M.E. 

This  set  of  five  volumes  contains  about  2,500  pages  with  thousands  of  illustrations,  including 
diagrammatic  and  sectional  drawings  with  full  explanatory  details.  This  W9rk  covers  the 
entire  practice  of  Civil  and  Mechanical  Engineering.  The  best  known  experts  in  all  branches 
of  engineering  have  contributed  to  these  volumes.  The  Cyclopedia  is  admirably  well  adapted 
to  the  needs  of  the  beginner  and  the  self-taught  practical  man,  as  well  as  the  mechanical 
engineer,  designer,  draftsman,  shop  superintendent,  foreman,  and  machinist.  The  work  will 
be  found  a  means  of  advancement  to  any  progressive  man.  It  is  encyclopedic  in  scope,  thor- 
ough and  practical  in  its  treatment  on  technical  subjects,  simple  and  clear  in  its  descriptive 
matter,  and  without  unnecessary  technicalities  or  formulae.  The  articles  are  as  brief  as  may 
be  and  yet  give  a  reasonably  clear  and  explicit  statement  of  the  subject,  and  are  written  by 
men  who  have  had  ample  practical  experience  in  the  matters  of  which  they  write.  It  tells 
you  all  you  want  to  know  about  engineering  and  tells  it  so  simply,  so  clearly,  so  concisely,  that 
one  cannot  help  but  understand.  As  a  work  of  reference  it  is  without  a  peer.  Complete 
set  of  five  volumes,  price  . $25 .00 

The  Modern  Machinist.    By  JOHN  T.  USHER. 

This  is  a  book,  showing  by  plain  description  and  by  profuse  engravings  made  expressly  for 
the  work,  all  that  is  best,  most  advanced,  and  of  the  highest  efficiency  in  modern  machine- 
shop  practice,  tools  and  implements,  showing  the  way  by  which  and  through  which,  as  Mr. 
Maxim  says,  "American  machinists  have. become  and  are  the  finest  mechanics  in  the  world. 
Indicating  as  it  does,  in  every  line,  the  familiarity  of  the  author  with  every  detail  of  daily 
experience  in  the  shop,  it  cannot  fail  to  be  of  service  to  any  man  practically  connected  with 
the  shaping  or  finishing  of  metals. 

There  is  nothing  experimental  or  visionary  about  the  book,  all  ^devices  being  in  actual  use 
and  giving  good  results.  It  might  be  called  a  compendium  of  shop  methods,  showing  a 
variety  of  special  tools  and  appliances  which  will  give  new  ideas  to  many  mechanics,  from 
the  superintendent  down  to  the  man  at  the  bench.  It  will  be  found  a  valuable  addition  to 
any  machinist's  library,  and  should  be  consulted  whenever  a  new  or  difficult  job  is  to  be 
done,  whether  it  is  boring,  milling,  turning,  or  planing,  as  they  are  all  treated  in  a  practical 
manner.  Fifth  edition.  320  pages.  250  illustrations.  Price §2.50 


CATALOGUE    OF    GOOD,     PRACTICAL     BOOKS          25 

THE  WHOLE  FIELD  OF  MECHANICAL  MOVEMENTS 
COVERED  BY  MR.  HISCOX'S  TWO  BOOKS 

We  publish  two  books  by  Gardner  D.  Hiscox  that  will  keep  you  from  "inventing'1  things  that  have 
been  done  before,  and  suggest  ways  of  doing  things  that  you  have  not  thought  of  before.  Many  a 
man  spends  time  and  money  pondering  over  some  mechanical  problem,  only  to  learn,  after  he 
has  solved  the  problem,  that  the  same  thing  has  been  accomplished  and  put  in  practice  by  others 
long  before.  Time  and  money  spent  in  an  effort  to  accomplish  what  has  already  been  accomplished 
are  time  and  money  LOST.  The  whole  field  of  mechanics,  every  known  mechanical  movement, 
and  practically  every  device  are  covered  by  these  two  books.  If  the  thing  you  want  has  been  invented, 
it  is  illustrated  in  them.  If  it  hasn't  been  invented,  then  you'll  find  in  them  the  nearest  things 
to  what  you  want,  some  movements  or  devices  that  will  apply  in  your  case,  perhaps;  or  which 
will  give  you  a  key  from  which  to  work.  No  book  or  set  of  books  ever  published  is  of  more  real 
value  to  the  Inventor,  Draftsman,  or  practical  Mechanic  than  the  two  volumes  described  below. 

Mechanical  Movements,  Powers,  and  Devices.    By  GARDNER  D.  Hiscox. 

This  is  a  collection  of  1,890  engravings  of  different  mechanical  motions  and  appliances,  ac- 
companied by  appropriate  text,  making  it  a  book  of  great  value  to  the  inventor,  the  drafts- 
man, and  to  all  readers  with  mechanical  tastes.  The  book  is  divided  into  eighteen  sections 
or  chapters,  in  which  the  subject-matter  is  classified  under 'the  following  heads:  Mechanical 
Powers;  Transmission  of  Power;  Measurement  of  Power;  Steam  Power;  Air  Power  Appli- 
ances; Electric  Power  and  Construction;  Navigation  and  Roads;  Gearing;  Motion  and 
Devices;  Controlling  Motion;  Horological;  Mining;  Mill  and  Factory  Appliances;  Con- 
struction and  Devices;  Drafting  Devices;  Miscellaneous  Devices,  etc.  15th  Edition.  400 
octavo  pages.  Price $3.00 

Mechanical  Appliances,  Mechanical  Movements  and  Novelties  of  Construc- 
tion.    By  GARDNER  D.  Hiscox. 

This  is  a  supplementary  volume  to  the  one  upon  mechanical  movements.  Unlike  the  first 
volume,  which  is  more  elementary  in  character,  this  volume  contains  illustrations  and  de- 
scriptions of  many  combinations  of  motions  and  of  mechanical  devices  and  appliances  found 
in  different  lines  of  machinery,  each  device  being  shown  by  a  line  drawing  with  a  description 
showing  its  working  parts  and  the  method  of  operation.  From  the  multitude  of  devices  de- 
scribed and  illustrated  might  be  mentioned,  in  passing,  such  items  as  conveyors  and  elevators, 
Pony  brakes,  thermometers,  various  types  of  boilers,  solar  engines,  oil-fuel  burners,  condensers, 
evaporators,  Corliss  and  other  valve  gears,  governors,  gas  engines,  water  motors  of  various 
descriptions,  air  ships,  motors  and  dynamos,  automobile  and  motor  bicycles,  railway  lock 
signals,  car  couplers,  link  and  gear  motions,  ball  bearings,  breech-block  mechanism  for  heavy 
guns,  and  a  large  accumulation  of  others  of  equal  importance.  One  thousand  specially  made 
engravings.  396  octavo  pages.  Fourth  edition.  Price $3.00 

Machine-Shop  Tools  and  Shop  Practice.     By  W.  H.  VANDERVOORT/ 

A  work  of  555  pages  and  673  illustrations,  describing  in  every  detail  the  construction,  opera 
tion  and  manipulation  of  both  hand  and  machine  tools.  Includes  chapters  on  filing,  fit- 
ting and  scraping  surfaces;  on  drills,  reamers,  taps  and  dies;  the  lathe  and  its  tools:  planers, 
shapers,  and  their  tools;  milling  machines  and  cutters;  gear  cutters  and  gear  cutting;  drill- 
ing machines  and  drill  work;  grinding  machines  and  their  work;  hardening  and  tempering; 
gearing,  belting  and  transmission  machinery;  useful  data  and  tables.  Sixth  edition. 

Price $3.00 

Machine- Shop  Arithmetic.     By  COLVIN-CHENEY. 

This  is  an  arithmetic  of  the  things  you  have  to  do  with  daily.  It  tells  you  plainly  about: 
how  to  find  areas  in  figures;  how  to  find  surface  or  volume  of  balls  or  spheres;  handy  ways 
for  calculating;  about  compound  gearing;  cutting  screw  threads  on  any  lathe;  drilling  for 
taps;  speeds  of  drills;  taps,  emery  wheels,  grindstones,  milling  cutters,  etc.;  all  about  the 
Metric  system  with  conversion  tables;  properties  of  metals;  strength  of  bolts  and  nuts; 
decimal  equivalent  of  an  inch.  All  sorts  of  machine-shop  figuring  and  1,001  other  things, 
any  one  of  which  ought  to  be  worth  more  than  the  price  of  this  book  to  you,  as  it  saves  you 
the  trouble  of  bothering  the  boss.  6th  Edition.  131  pages.  Price 50  Cents 

Modern  Machine-Shop  Construction,  Equipment  and  Management.    By 

OSCAR  E.  PERRIGO. 

The  only  work  published  that  describes  the  .Modern  Shop  or  Manufacturing  Plant  from  the 
time  the  grass  is  growing  on  the  site  intended  for  it  until  the  finished  product  is  shipped.  Just 
the  book  needed  by  those  contemplating  the  erection  of  modern  shop  buildings,  the  rebuilding 
and  reorganization  of  old  ones,  or  the  introduction  of  Modern  Shop  Methods,  time  and  cost 
systems.  It  is  a  book  written  and  illustrated  by  a  practical  shop  man  for  practical  shop  men 
who  are  too  busy  to  read  theories  and  want  facts.  It  is  the  most  complete  all-round  book  of 
its  kind  ever  published.  Second  Edition,  Revised.  384  large  quarto  pages.  219  original  and 
specially  made  illustrations.  2nd  Revised  and  Enlarged  Edition.  Price  .......  $5  00 


26        THE    NORMAN    W.     HENLEY    PUBLISHING     CO. 

Modern  Milling  Machines:    Their  Design,  Construction,  and  Operation. 

By  JOSEPH  G.  HORNER. 

This  book  describes  and  illustrates  the  Milling  Machine  and  its  .work  in  such  a  plain,  clear 
and  forceful  manner,  and  illustrates  the  subject  so  clearly  and  completely,  that  the  up-to- 
date  machinist,  student  or  mechanical  engineer  cannot  afford  to  do  without  the  valuable 
information  which  it  contains.  It  describes  not  only  the  early  machines  of  this  class,  but  notes 
their  gradual  development  into  the  splendid  machines  of  the  present  day,  giving  the  design 
and  construction  of  the  various  types,  forms,  and  special  features  produced  by  prominent 
manufacturers,  American  and  foreign.  304  pages,  300  illustrations.  Cloth.  Price...  $4.00 

"  Shop  Kinks."     By  ROBERT  GRIMSHAW. 

A  book  of  400  pages  and  222  illustrations,  being  entirely  different  from  any  other  book  on 
machine-shop  practice.  Departing  from  conventional  style,  the  author  avoids  universal 
or  common  shop  usage  and  limits  his  work  to  showing  special  ways  of  doing  things  better, 
more  cheaply  and  more  rapidly  than  usual.  As  a  result  the  advanced  methods  of  represen- 
tative establishments  of  the  world  are  placed  at  the  disposal  of  the  reader.  This  book  shows 
the  proprietor  where  large  savings  are  possible,  and  how  products  may  be  improved.  To 
the  employee  it  holds  out  suggestions  that,  properly  applied,  will  hasten  his  advancement. 
No  shop  can  afford  to  be  without  it.  It  bristles  with  valuable  wrinkles  and  helpful  sugges- 
tions. It  will  benefit  all,  from  apprentice  to  proprietor.  Every  machinist,  at  any  age,  should 
study  its  pages.  Fifth  edition.  Price $2.50 

Threads  and  Thread  Cutting.    By  COLVIN  and  STABEL. 

This  clears  up  many  of  the  mysteries  of  thread-cutting,  such  as  double  and  triple  threads, 
internal  threads,  catching  threads,  use  of  hobs,  etc.  Contains  a  lot  of  useful  hints  and  several 
tables.  Third  edition.  Price 25  cent S 

MANUAL  TRAINING 

Economics  of  Manual  Training.    By  Louis  ROUILLION. 

.The  only  book  published  that  gives  just  the  information  needed  by  all  interested  in  Manual 
Training,  regarding  Buildings,  Equipment,  and  Supplies.  Shows  exactly  what  is  needed 
for  all  grades  of  the  work  from  the  Kindergarten  to  the  High  and  Normal  School.  Gives 
itemized  lists  of  everything  used  in  Manual  Training  Work  and  tells  just  what  it  ought  to 
cost.  Also  shows  where  to  buy  supplies,  etc.  Contains  174  pages,  and  is  fully  illustrated. 
Second  edition.  Price •. ; $1.50 


MARINE  ENGINEERING 

The  Naval  Architect's  and  Shipbuilder's  Pocket  Book  of  Formulae,  Rules, 
and  Tables  and  Marine  Engineer's  and  Surveyor's  Handy  Book  of 
Reference.  By  CLEMENT  MACKROW  and  LLOYD  WOOLLARD. 

The  eleventh  Revised  and  Enlarged  Edition  of  this  most  comprehensive  work  has  just  been 
issued.  It  is  absolutely  indispensable  to  all  engaged  in  the  Shipbuilding  Industry,  as  it  con- 
denses into  a  compact  form  all  data  and  formulae  that  are  ordinarily  required.  The  book  is 
completely  up  to  date,  including  among  other  subjects  a  section  on  Aeronautics.  750  pages, 
limp  leather  binding.  Price $5.00  net 

Marine  Engines  and  Boilers:   Their  Design  and  Construction.    By  DR.  G. 

BAUER,  LESLIE  S.  ROBERTSON  and  S.  BRYAN  DONKIN. 

In  the  words  of  Dr.  Bauer,  the  present  work  owes  its  origin  to  an  oft  felt  want  of  a  condensed 
treatise  embodying  the  theoretical  and  practical  rules  used  in  designing  marine  engines  and 
boilers.  The  need  of  such  a  work  has  been  felt  by  most  engineers  engaged  m  the  construction 
and  working  of  marine  engines,  not  only  by  the  younger  men,  but  also  by  those  of  greater  ex- 
perience. The  fact  that  the  original  German  work  was  written  by  the  chief  engineer  ot  the 
famous  Vulcan  Works,  Stettin,  is  in  itself  a  guarantee  that  this  book  is  m  all  respects  thor- 
oughly up-to-date,  and  that  it  embodies  all  the  information  which  is  necessary  for  the  design 
and  construction  of  the  highest  types  of  marine  engines  and  b9ilers.  It  may  be  said  that  the 
motive  power  which  Dr.  Bauer  has  placed  in  the  fast  German  liners  that  have  been  turned  out 
of  late  years  from  the  Stettin  Works  represent  the  very  best  practice  in  marine  engineering  ot 
the  present  day.  The  work  is  clearly  written,  thoroughly  systematic,  theoretically  sound; 
while  the  character  of  the  plans,  drawings,  tables,  and  statistics  is  without  reproach.  Ine 
illustrations  are  careful  reproductions  from  actual  working  drawings,  with  some  well- executed 
photographic  views  of  completed  engines  and  boilers.  744  pages,  550  illustrations  and  num- 
erous tables.  Cloth.  Price $9.00  net 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    27 


MINEYG 


Ore  Deposits,  with  a  Chapter  on  Hints  to  Prospectors.    By  J.  P.  JOHNSON. 

This  book  gives  a  condensed  account  of  the  ore  deposits  at  present  known  in  South  Africa. 
It  is  also  intended  as  a  guide  to  the  prospector.  Only  an  elementary  knowledge  of  geology 
and  some  mining  experience  are  necessary  in  order  to  understand  this  work.  With  these 
qualifications,  it  will  materially  assist  one  in  his  search  for  metalliferous  mineral  occurrences 
and,  so  far  as  simple  ores  are  concerned,  should  enable  one  to  form  some  idea  of  the  possi- 
bilities of  any  he  may  find.  Illustrated.  Cloth.  Price $2  00 

Practical  Coal  Mining.    By  T.  H.  COCKIN. 

An  important  work,  containing  428  pages  and  213  illustrations,  complete  with  practical  details, 
which  will  intuitively  impart  to  the  reader  not  only  a  general  knowledge  of  the  principles 
of  coal  mining,  but  also  considerable  insight  into  allied  subjects.  The  treatise  is  positively 
up-to-date  in  every  instance,  and  should  be  in  the  hands  of  every  colliery  engineer,  geologist, 
mine  operator,  superintendent,  foreman,  and  all  others  who  are  interested  in  or  connected  with 
the  industry.  3d  Edition.  Cloth.  Price $2.50 

Physics  and  Chemistry  of  Mining.    By  T.  H.  BYROM. 

A  practical  work  for  the  use  of  all  preparing  for  examinations  in  mining  or  qualifying  for 
colliery  managers'  certificates.  The  aim  of  the  author  in  this  excellent  book  is  to  place  clearly 
before  the  reader  useful  and  authoritative  data  which  will  render  him  valuable  assistance  in 
his  studies.  The  only  work  of  its  kind  published.  The  information  incorporated  in  it  will 
prove  of  the  greatest  practical  utility  to  students,  mining  engineers,  colliery  managers,  and 
all  others  who  are  specially  interested  in  the  present-day  treatment  of  mining  problems.  160 
pages,  illustrated.  Price  $2.00 

PATTERN  MAKING 

Practical  Pattern  Making.    By  F.  W.  BARROWS. 

This  book,  now  in  its  second  edition,  is  a  comprehensive  and  entirely  practical  treatise  on  the 
subject  of  pattern  making,  illustrating  pattern  work  in  both  wood  and  metal,  and  with  definite 
instructions  on  the  use  of  plaster  of  parts  in  the  trade.  It  gives  specific  and  detailed  descrip- 
tions of  the  materials  used  by  pattern  makers,  and  describes  the  tools,  both  those  for  the 
bench  and  the  more  interesting  machine  tools,  having  complete  chapters  on  the  Lathe,  the 
Circular  Saw,  and  the  Band  Saw.  It  gives  many  examples  of  pattern  work,  each  one  fully 
illustrated  and  explained  with  much  detail.  These  examples,  in  their  great  variety,  offer  much 
that  will  be  found  of  interest  to  all  pattern  makers,  and  especially  to  the  younger  ones,  who 
are  seeking  information  on  the  more  advanced  branches  of  their  trade. 

In  this  second  edition  of  the  work  will  be  found  much  that  is  new,  even  to  those  who  have 
long  practised  this  exacting  trade.  In  the  description  of  patterns  as  adapted  to  the  Moulding 
Machine  many  difficulties  which  have  long  prevented  the  rapid  and  economical  production  of 
castings  are  overcome;  and  this  great,  new  branch  of  the  trade  is  given  much  space.  Strip- 
ping plate  and  stool  plate  work  and  the  less  expensive  vibrator,  or  rapping  plate  work,  are 
all  explained  in  detail. 

Plain,  every-day  rules  for  lessening  the  cost  of  patterns,  with  a  complete  system  of  cost 
keeping,  a  detailed  method  of  marking,  applicable  to  all  branches  of  the  trade,  with  com- 
plete information  showing  what  the  pattern  is,  its  specific  title,  its  cost,  date  of  production, 
material  of  which  it  is  made,  the  number  of  pieces  and  core-boxes,  and  its  location  in  the 
pattern  safe,  all  condensed  into  a  most  complete  card  record,  with  cross  index. 
The  book  closes  with  an  original  and  practical  method  for  the  inventory  and  valuation  of 
patterns.  Containing  nearly  350  pages  and  170  illustrations.  Price $2*00 


PERFUMERY 

Perfumes  and  Cosmetics:  Their  Preparation  and  Manufacture.    By  G.  W. 

ASKINSON,  Perfumer. 

A  comprehensive  treatise,  in  which  there  has  been  nothing  omitted  that  could  be  of  value 
to  the  perfumer  or  manufacturer  of  toilet  preparations.  Complete  directions  for  making 
handkerchief  perfumes,  smelling-salts,  sachets,  fumigating  pastilles;  preparations  for  the 
care  of  the  skin,  the  mouth,  the  hair,  cosmetics,  hair  dyes  and  other  toilet  articles  are  given, 
also  a  detailed  description  of  aromatic  substances;  their  nature,  tests  of  purity,  and  whole- 
some manufacture,  including  a  chapter  on  synthetic  products,  with  formulas  for  their  use. 
A  book  of  general  as  well  as  professional  interest,  meeting  the  wants  not  only  of  the  drug- 

rt  and  perfume  manufacturer,  but  also  of  the  general  public.  Among  the  contents  are: 
The  History  of  Perfumery.  2.  About  Aromatic  Substances  in  General.  3.  Odors  from 
the  Vegetable  Kingdom.  4.  The  Aromatic  Vegetable  Substances  Employed  in  Perfumery. 
5.  The  Animal  Substances  Used  in  Perfumery.  6.  The  Chemical  Products  Used  in  Perfumery. 
7.  The  Extraction  of  Odors.  8.  The  Special  Characteristics  of  Aromatic  Substances.  9.  The 
Adulteration  of  Essential  Oils  and  Their  Recognition.  10.  Synthetic  Products.  11.  Table 
of  Physical  Properties  of  Aromatic  Chemicals.  12.  The  Essences  or  Extracts  Employed 
in  Perfumery.  13.  Directions  for  Making  the  Most  Important  Essences  and  Extracts. 


28        THE     NORMAN    W.     HENLEY    PUBLISHING     CO. 

14.  The  Division  of  Perfumery.  15.  The  Manufacture  of  Handkerchief  Perfumes.  16.  For- 
mulas for  Handkerchief  Perfumes.  "  17.  Ammoniacal  and  Acid  Perfumes.  18.  Dry  Per- 
fumes. 19.  Formulas  for  Dry  Perfumes.  20.  The  Perfumes  Used  for  Fumigation.  21.  An- 
tiseptic and  Therapeutic  Value  of  Perfumes.  22.  Classification  of  Odors.  23.  Some  Special 
Perfumery  Products.  24.  Hygiene  and  Cosmetic  Perfumery.  25.  Preparations  for  the  Care 
of  the  Skin.  26.  Manufacture  of  Casein.  27.  Formulas  for  Emulsions.  28.  Formulas  for 
Cream.  29.  Formulas  for  Meals, '  Pastes  and  Vegetable  Milk.  30.  Preparations  Used  for 
the  Hair.  31.  Formulas  for  Hair  Tonics  and  Restorers.  32.  Pomades  and  Hair  Oils. 
33.  Formulas  for  the  Manufacture  of  Pomades  and  Hair  Oils.  34.  Hair  Dyes  and  Depila- 
tories. 35.  Wax  Pomades,  Bandolines  and  Bri'lliantines.  36.  Skin  Cosmetics  and 
Face  Lotions.  37.  Preparations  for  the  Nails.  38.  Water  Softeners  and  Bath  Salts.  39. 
Preparations  for  the  Care  of  the  Mouth.  40.  The  Colors  Used  in  Perfumery.  41.  The  Uten- 
sils Used  in  the  Toilet.  Fourth  edition,  much  enlarged  and  brought  up  to  date.  Nearly 
400  pages,  illustrated.  Price $5.00 

WHAT  IS  SAID  OF  THIS  BOOK: 

"The  most  satisfactory  work  on  the  subject  of  Perfumery  that  we  have  ever  seen." 
"We  feel  safe  in  saying  that. here  is  a  book  on  Perfumery  that  will  not  disappoint  you,  for 
it  has  practical  and  excellent  formulae  that  are  within  your  ability  to  prepare  readily." 
"We  recommend  the  volume  as  worthy  of  confidence,  and  say  that  no  purchaser  will  be  dis- 
appointed in  securing  from  its  pages  good  value  for  its  cost,  and  a  large  dividend  on  the  same, 
even  if  he  should  use  but  one  per  cent,  of  its  working  formulae.    There  is  money  in  it  for  every 
user  of  its  information." — Pharmaceutical  Record. 

PLUMBING 


Mechanical  Drawing  for  Plumbers.    By  R.  M.  STAEBUCK. 

A  concise,  comprehensive  and  practical  treatise  on  the  subject  of  mechanical  drawing  in  its 
various  modern  applications  to  the  work  of  all  who  are  in  any  way  connected  with  the  plumb- 
ing trade.  Nothing  will  so  help  the  plumber  in  estimating  and  in  explaining  work  to  cus- 
tomers and  workmen  as  a  knowledge  of  drawing,  and  to  the  workman  it  is  of  inestimable 
value  if  he  is  to  rise  above  his  position  to  positions  of  greater  responsibility.  Among  the 
chapters  contained  are:  1.  Value  to  plumber  of  knowledge  of  drawing;  tools  required  and 
their  use;  common  views  needed  in  mechanical  drawing.  2.  Perspective  versus  mechanical 
drawing  in  showing  plumbing  construction.  3.  Correct  and  incorrect  methods  in  plumbing 
drawing;  plan  and  elevation  explained.  4.  Floor  and  cellar  plans  and  elevation;  scale 
drawings;  use  of  triangles.  5.  Use  of  triangles;  drawing  of  fittings,  traps,  etc.  6.  Drawing 
plumbing  elevations  and  fittings.  7.  Instructions  in  drawing  plumbing  elevations.  8.  The 
drawing  of  plumbing  fixtures;  scale  drawings.  9.  Drawings  of  fixtures  and  fittings.  10.  Ink- 
•  •  ing  of  drawings.  11.  Shading  of  drawings.  12.  Shading  of  drawings.  13.  Sectional  drawings; 
drawing  of  threads.  14.  Plumbing  elevations  from  architect's  plan.  15.  Elevations  of  sepa- 
rate parts  of  the  plumbing  system.  16.  Elevations  from  the  architect's  plans.  17.  Drawings 
of  detail  plumbing  connections.  18.  Architect's  plans  and  plumbing  elevations  of  residence. 
19.  Plumbing  elevations  of  residence  (continued);  plumbing  plans  for  cottage.  20.  Plumbing 
elevations;  'roof  connections.  21.  Plans  and  plumbing  elevations  for  six-flat  building.  22. 
Drawing  of  various  parts  of  the  plumbing  system;  use  of  scales.  23.  Use  of  architect's  scales. 
24.  Special  features  in  the  illustrations  of  country  plumbing.  25.  Drawing  of  wrought-iron 
piping,  valves,  radiators,  coils,  etc.  26.  Drawing  of  piping  to  illustrate  heating  systems. 
150  illustrations.  Price $1.50 

Modern  Plumbing  Illustrated.    By  R.  M.  STARBUCK. 

This  book  represents  the  highest  standard  of  plumbing  work.  It  has  been  adopted  and  used 
as  a  reference  book  by  the  United  States  Government  in  its  sanitary  work  in  Cuba,  Porto 
Rico  and  the  Philippines,  and  by  the  principal  Boards  of  Health  of  the  United  States  and 
Canada. 

It  gives  connections,  sizes  and  working  data  for  all  fixtures  and  groups  of  fixtures.  It  is  help- 
ful to  the  master  plumber  in  demonstrating  to  his  customers  and  in  figuring  work.  It  gives 
the  mechanic  and  student  quick  and  easy  access  to  the  best  modern  plumbing  practice.  Sug- 
gestions for  estimating  plumbing  construction  are  contained  in  its  pages.  This  book  repre- 
sents, in  a  word,  the  latest  and  best  up-to-date  practice  and  should  be  in  the  hands  of  every 
architect,  sanitary  engineer  and  plumber  who  wishes  to  keep  himself  up  to  the  minute  on 
this  important  feature  of  construction.  Contains  following  chapters,  each  illustrated  with  a 
full-page  plate:  Kitchen  sink,  laundry  tubs,  vegetable  wash  sink;  lavatories,  pantry  sinks, 
contents  of  marble  slabs;  bath  tub,  foot  and  sitz  bath,  shower  bath;  water  closets,  venting 
of  water  closets;  low-down  water  closets,  water  closets  operated  by  flush  valves,  water  closet 
range;  slop  sink,  urinals,  the  bidet;  hotel  and  restaurant  sink,  grease  trap;  refrigerators, 
safe  wastes,  laundry  waste,  lines  of  refrigerators,  bar  sinks,  soda  fountain  sinks;  horse  stall, 
frost-proof  water  closets;  connections  for  S  traps,  venting;  connections  for  drum  traps; 
soil-pipe  connections;  supporting  of  soil  pipe;  main  trap  and  fresh-air  inlet;  floor  drains  and 
cellar  drains,  subsoil  drainage;  water  closets  and  floor  connections;  local  venting;  connections 
for  bath  rooms;  connections  for  bath  rooms,  continued;  examples  of  poor  practice;  roughing 
work  ready  for  test;  testing  of  plumbing  systems;  method  of  continuous  venting;  continuous 
venting  for  two-floor  work;  continuous  venting  for  two  lines  of  fixtures  on  three  or  more 
floors;  continuous  venting  of  water  closets;  plumbing  for  cottage  house;  construction  for 
cellar  piping;  plumbing  for  residence,  use  of  special  fittings;  plumbing  for  two-flat  house; 
plumbing  for  apartment  building",  plumbing  for  double  apartment  building;  plumbing  for 
office  building;  plumbing  for  public  toilet  rooms;  plumbing  for  public  toilet  rooms,  con- 
tinued; plumbing  for  bath  establishment;  plumbing  for  engine  house,  factory  plumbing; 
automatic  flushing  for  schools,  factories,  etc.;  use  of  flushing  valves;  urinals  for  public  toilet 
rooms;  the  Durham  system,  the  destruction  of  nines  bv  electrolysis;  construction  of  work 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    29 

without  use  of  lead;  automatic  sewage  lift;  automatic  sump  tank;  country  plumbing; 
construction  of  cesspools;  septic  tank  and  automatic  sewage  siphon;  water  supply  for 
country  house;  thav/ing  of  water  mains  and  service  by  electricity;  double  boilers;  hot 
water  supply  of  lar^e  buildings;  automatic  control  of  hot-water  tank;  suggestions  for 
estimating  plumbing  construction.  407  ootavo  pages,  fully  illustrated  by  57  full-page 
engravings.  Third,  revised  and  enlarged  edition,  just  issued.  Price $4.00 

Standard  Practical  Plumbing.     By  R.  M.  STARED  CK. 

A  complete  practical  treatise  of  450  pages,  covering  the  subject  of  Moderr  Plumbing  in  al>  its 
branches,  a  large  amount  of  space  being  devoted  to  a  very  complete  and  practical  treatment  of 
the  subject  of  Hot  Water  Supply  and  Circulation  and  Range  Boiler  Work.  Its  thirty  Chapters 
include  about  every  phase  of  the  subject  one  can  think  of,  making  it  an  ii.dispenEabif>  work  to 
the  master  plumber,  the  journeyman  plumber,  and  the  apprentice  plumber,  containing  chap- 
ters on:  the  plumber's  tools;  wiping  solder;  composition  and  use;  joint  wiping;  lead  work; 
traps;  siphonage  of  traps;  venting;  continuous  venting;  house  sewer  and  sewer  connections; 
house  drain;  soil  piping,  roughing;  main  trap  and  fresh  air  inlet;  floor,  yard,  cellar  drains, 
rain  leaders,  etc. ;  fixture  wastes;  water  closets;  ventilation;  improved  plumbing  connections; 
residence  plumbing;  plumbing  for  hotels*  schools,  factories,  stables,  etc.;  modern  country 
plumbing;  filtration  of  sewage  and  water  supply '  hot  and  cold  supply;  range  boilers;  circula- 
tion; circulating  pipes;  range  boiler  problems;  hot  water  for  large  buildings;  water  lift  and 
its  use;  multiple  connections  for  hot  water  boilers;  heating  of  radiation  by  supply  system; 
theory  for  the  plumber;  drawing  for  the  plumber.  Fully  illustrated  by  347  engravings. 

$3.00 

RECIPE  BOOK 


Henley's  Twentieth  Century  Book  of  Recipes,  Formulas  and  Processes. 

Edited  by  GARDNER  D.  Hiscox. 

The  most  valuable  Tecbno-chemical  Formula  Book  published,  including  over  10,000  selected 
scientific,  chemical,  technological,  and  practical  recipes  and  processes. 

This  is.  the  most  complete  Book  of  Formulas  ever  published,  giving  thousands  of  recipes  for 
the  manufacture  of  valuable  articles  for  everyday  use.  Hints,  Helps,  Practical  Ideas,  and 
Secret  Processes  are  revealed  within  its  pages.  It  covers  every  branch  of  the  useful  arts  and 
tells  thousands  of  ways  of  making  money,  and  is  just  the  book  everyone  should  have  at  his 
command. 

Modern  in  its  treatment  of  every  subject  that  properly  falls  within  its  scope,  the  book  may 
truthfully  be  said  to  present  the  very  latest  formulas  to  be  found  in  the  arts  and  industries, 
and  to  retain  those  processes  which  long  experience  has  proven  worthy  of  a  permanent  record. 
TO  present  here  even  a  limited  number  of  the  subjects  which  find  a  place  in  this  valuable  work 
would  be  difficult.  Suffice  to  say  that  in  its  pages  will  be  found  matter  of  intense  interest  and 
immeasurably  practical  value  to  the  scientific  amateur  and  to  him  who  wishes  to  obtain  a 
knowledge  of  the  many  processes  used  in  the  arts,  trades  and  manufacture,  a  knowledge 
which  will  render  his  pursuits  more  instructive  and  remunerative.  Serving  as  a 
reference  book  to  the  small  and  large  manufacturer  and  supplying  intelligent  seekers  with  the 
information  necessary  to  conduct  a  process,  the  work  will  be  found  of  inestimable  worth  to 
the  Metallurgist,  the  Photographer,  the  Perfumer,  the  Painter,  the  Manufacturer  of  Glues, 
Pastes,  Cements,  and  Mucilages,  the  Compounder  of  Alloys,  the  Cook,  the  Physician,  the 
Druggist,  the  Electrician,  the  Brewer,  the  Engineer,  the  Foundryman,  the  Machinist,  the 
Potter,  the  Tanner,  the  Confectioner,  the  Chiropodist,  the  Manicurist,  the  Manufacturer  of 
Chemical  Novelties  and  Toilet  Preparations,  the  Dyer,  the  Electroplater,  the  Enameler,  the 
Engraver,  the  Provisioner,  the  Glass  Worker,  the  Goldbeater,  the  Watchmaker,  the  Jeweler, 
the  Hat  Maker,  the  Ink  Manufacturer,  the  Optician,  the  Farmer,  the  Dairyman,  the  Paper 
Maker,  the  Wood  and  Metal  Worker,  the  Chandler  and  Soap  Maker,  the  Veterinary  Surgeon, 
and  the  Technologist  in  general. 

A  mine  of  information,  and  up-to-date"in  every  respect.  A  book  which  will  prove  of  value 
to  EVERYONE,  as  it  covers  every  branch  of  the  Useful  Arts.  Every  home  needs  this  book; 
every  office,  every  factory,  every  store,  every  public  and  private  enterprise — EVERYWHERE 
— should  have  a  copy.  800  pages.  Price $3.00 

WHAT  IS  SAID  OF  THIS  BOOK: 

"Your  Twentieth  Century  Book  of  Recipes,  Formulas,  and  Processes  duly  received.  I  am 
glad  to  have  a  copy  of  it,  and  if  I  could  not  replace  it,  money  couldn't  buy  it.  It  is  the  best 
thing  of  the  sort  I  ever  saw."  (Signed)  M.  E.  TRUX,  Sparta,  Wis. 


"  There  are  few  persons  who  would  not  be  able  to  find  in  the  book  some  single  formula  that 
would  repay  several  times  the  cost  of  the  book." — Merchants'  Record  and  Show  Window. 

"  I  purchased  your  book, '  Henley's  Twentieth  Century  Book  of  Recipes,  Formulas  and  Proc- 
esses,' about  a  year  ago  and  it  is  worth  its  weight  in  gold." — WM.  H.  MURRAY,  Bennington,  Vt. 

"ONE  OF  THE  WORLD'S  MOST  USEFUL  BOOKS" 

"Some  time  ago  I  got  one  of  your  'Twentieth  Century  Books  of  Foitnulas,'  and  have  made 
my  living  from  it  ever  since.  I  am  alone  since  my  husband's  death  with  two  small  children 
to  care  for  and  am  trying  so  hard  to  support  them.  I  have  customers  who  take  from  me 
Toilet  Articles  I  put  up,  following  directions  given  in  the  book,  and  I  have  found  everyone  of 
them  to  be  fine." — MRS.  J.  H.  MCMAKEN,  West  Toledo,  Ohio. 


30    THE  NORMAN  W.  HENLEY  PUBLISHING  CO. 


RUBBER 


Rubber  Hand  Stamps  and  the  Manipulation  of  India  Rubber.     By  T. 

O'CONOR  SLOANE. 

This  book  gives  full  details  on  all  points,  treating  in  a  concise  and  simple  manner  the  elements 
of  nearly  everything  it  is  necessary  to  understand  for  a  commencement  in  any  branch  of  the 
India  Rubber  Manufacture.  The  making  of  all  kinds  of  Rubber  Hand  Stamps,  Small  Articles 
of  India  Rubber,  U.  S.  Government  Composition,  Dating  Hand  Stamps,  the  Manipulation  of 
Sheet  Rubber,  Toy  Balloons,  India  Rubber  Solutions,  Cements,  Blackings,  Renovating, 
Varnish,  and  Treatment  for  India  Rubber  Shoes,  etc.;  the  Hektograph  Stamp  Inks,  and  Mis- 
cellaneous Notes,  with  a  Short  Account  of  the  Discovery,  Collection  and  Manufacture  of  India 
Rubber,  are  set  forth  in  a  manner  designed  to  be  readily  understood,  the  explanations  being 
plain  and  simple.  Including  a  chapter  on  Rubber  Tire  Making  and  Vulcanizing;  also  a 
chapter  on  the  uses  of  rubber  in  Surgery  and  Dentistry.  3rd  Revised  and  Enlarged  Edition. 
175  pages.  Illustrated  $1.00 

SAWS 

Saw  Filing  and  Management  of  Saws.    By  ROBERT  GRIMSHAW. 

A  practical  hand-book  on  filing,  gumming,  swaging,  hammering,  and  the  brazing  of  band 
Baws,  the  speed,  work,  and  power  to  run  circular  saws,  etc.  A  handy  book  for  those  who  have 
charge  of  saws,  or  for  those  mechanics  who  do  their  own  filing,  as  it  deals  with  the  proper 
shape  and  pitches  of  saw  teeth  of  all  kinds  and  gives  many  useful  hints  and  rules  for  gumming, 
setting,  and  filing,  and  is  a  practical  aid  to  those  who  use  saws  for  any  purpose.  Complete 
tables  of  proper  shape,  pitch,  and  saw  teeth  as  well  as  sizes  and  number  of  teeth  of  various 
saws  are  included.  3rd  Edition,  Revised  and  Enlarged.  Illustrated.  Price $1.00 


STEAM  ENGINEERING 

American  Stationary  Engineering.    By  W.  E.  CRANE. 

This  book  begins  at  the  boiler  room  and  takes  in  the  whole  power  plant.  A  plain  talk  on 
eyery-day  work  about  engines,  boilers,  and  their  accessories.  It  is  not  intended  to  be  scien- 
tific or  mathematical.  All  formulas  are  in  simple  form  so  that  any  one  understanding  plain 
arithmetic  can  readily  understand  any  of  them.  The  author  has  made  this  the  most  practical 
book  in  print;  has  given  the  results  of  his  years  of  experience,  and  has  included  about  all  that 
has  to  do  with  an  engine  room  or  a  power  plant.  You  are  not  left  to  guess  at  a  single  point. 
You  are  shown  clearly  what  to  expect  under  the  various  conditions;  how  to  secure  the  best 
results;  ways  of  preventing  "shut  downs"  and  repairs;  in  short,  all  that  goes  to  make  up  the 
requirements  of  a  good  engineer,  capable  of  taking  charge  of  a  plant.  It's  plain  enough,  for 
practical  men  and  yet  of  yalue  to  those  high  in  the  profession. 

A  partial  list  of  contents  is:  The  boiler  room,  cleaning  boilers,  firing,  feeding;  pumps,  inspec- 
tion and  repair ;  chimneys,  sizes  and  cost;  piping;  mason  work;  foundations;  testing  cement; 


tools;  pistons  and  piston  rings;  bearing  metal;  hardened  copper;  drip  pipes  from  cylinder 
jacket;  belts,  how  made,  care  of;  oils;  greases;  testing  lubricants;  rules  and  tables,  in- 
cluding steam  tables;  areas  of  segments;  squares  and  square  roots;  cubes  and  cube  root; 
areas  and  circumferences  of  circles.  Notes  on:  Brick  work;  explosions;  pumps;  pump 
valves;  heaters,  economizers;  safety  valves;  lap,  lead,  and  clearance.  Has  a  complete  ex- 
amination for  a  license,  etc.,  etc.  3rd  Edition.  345  pages,  illustrated.  Price  .  .  . 


Engine  Runner's  Catechism.     By  ROBERT  GRIMSHAW. 

A  practical  treatise  for  the  stationary  engineer,  telling  how  to  erect,  adjust,  and  run  the 
principal  steam  engines  in  use  in  the  United  States.  Describing  the  principal  features  of  vari- 
ous special  and  well-known  makes  of  engines:  Temper  Cut-off,  Snipping  and  Receiving  Founda- 
tions, Erecting  and  Starting,  Valve  Setting,  Care  and  Use,  Emergencies,  Erecting  and  Ad- 
justing Special  Engines. 

The  questions  asked  throughout  the  catechism  are  plain  and  to  the  point,  and  the  answers 
are  given  in  such  simple  language  as  to  be  readily  understood  by  anyone.  All  the  instructions 
given  are  complete  and  up-to-date;  and  they  are  written  in  a  popular  style,  without  any 
technicalities  or  mathematical  formulae.  The  work  is  of  a  handy  size  for  the  pocket,  clearly 
and  well  printed,  nicely  bound,  and  profusely  illustrated. 

To  young  engineers  this  catechism  will  be  of  great  value,  especially  to  those  who  may  bg 
preparing  to  go  forward  to  be  examined  for  certificates  of  competency;  and  to  engineers 
generally  it  will  be  of  no  little  service,  as  they  will  find  in  this  volume  more  really  practical 
and  useful  information  than  is  to  be  found  anywhere  else  within  a  like  compass.  387  pages. 
7th  Edition.  Price  ................  ..............  $2.00 


CATALOGUE    OF    GOOD,     PRACTICAL     BOOKS          31 

Modern   Steam   Engineering   in   Theory   and   Practice.    By   GARDNER   D. 
Hiscox. 

This  is  a  complete  and  practical  work  issued  for  Stationary  Engineers  and  Firemen,  dealing 
with  the  care  and  management  of  boilers,  engines,  pumps,  superheated  steam,  refrigerating 
machinery,  dynamos,  motors,  elevators,  air  compressors,  and  all  other  branches  with  which 
the  modern  engineer  must  be  familiar.  Nearly  200  questing  with  their  answers  on  steam 
and  electrical  engineering,  likely  to  be  asked  by  the  Examining  Board,  are  included. 
Among  the  chapters  are:  Historical:  steam  and  its  properties;  appliances  for  the  generation 
of  steam;  types  of  boilers;  chimney  and  its  work;  heat  economy  of  the  feed  water;  steam 
pumps  and  their  work;  incrustation  and  its  work;  steam  above  atmospheric  pressure;  flow 
of  steam  from  nozzles;  superheated  steam  and  its  work;  adiabatic  expansion  of  steam;  indi- 
cator and  its  work;  steam  engine  proportions;  slide  valve  engines  and  valve  motion;  Corliss 
engine  and  its  valve  gear;  compound  engine  and  its  theory;  triple  and  multiple  expansion 
engine;  steam  turbine;  refrigeration;  elevators  and  their  management;. cost  of  power;  steam 
engine  troubles;  electric  power  and  electric  plants.  487  pages,  405  engravings.  3rd  Edition. 
Price $3.00 

Steam  Engine  Catechism.    By  ROBERT  GRIMSHAW. 

This  unique  volume  of  413  pages  is  not  only  a  catechism  on  the  question  and  answer  principle 
but  it  contains  formulas  and  worked-out  answers  for  all  the  Steam  problems  that  appertain  to 
operation  and  management  of  the  Steam  Engine.  Illustrations  of  various  valves  and  valve 
gear  with  their  principles  of  operation  are  given.  Thirty-four  Tables  that  are  indispensable 
to  every  engineer  and  fireman  that  wishes  to  be  progressive  and  is  ambitious  to  become  master 
of  his  calling  are  within  its  pages.  It  is  a  most  valuable  instructor  in  the  service  of  Steam 
Engineering.  Leading  engineers  have  recommended  it  as  a  valuable  educator  for  the  begin- 
ner as  well  as  a  reference  book  for  the  engineer.  It  is  thoroughly  indexed  for  every  detail. 
Every  essential  question  on  the  Steam  Engine  with  its  answer  is  contained  in  this  valuable 
work.  16th  Edition.  Price  : 82.00 

Steam  Engineer's  Arithmetic.    By  COLVIN-CHENEY. 

A  practical  pocket-book  for  the  steam  engineer.  Shows  how  to  work  the  problems  of  the 
engine  room  and  shows  "why."  Tells  how  to  figure  horsepower  of  engines  and  boilers;  area 
of  boilers;  has  tables  of  areas  and  circumferences;  steam  tables;  has  a  dictionary  of  engineering 
terms.  Puts  you  on  to  all  of  the  little  kinks  in  figuring  whatever  there  is  to  figure  around  a 
power  plant.  Tells  you  about  the  heat  unit;  absolute  zero;  adiabatic  expansion;  duty  of 
engines;  factor  of  safety;  and  a  thousand  and  one  other  things;  and  everything  is  plain  and 
simple — not  the  hardest  way  to  figure,  but  the  easiest.  2nd  Edition.  Price  .  .  50  Cents 

Engine  Tests  and  Boiler  Efficiencies.     By  J.  BUCHETTI. 

This  work  fully  describes  and  illustrates  the  method  of  testing  the  power  of  steam  engines, 
turbines  and  explosive  motors.  The  properties  of  steam  and  the  evaporative  power  of  fuels. 
Combustion  of  fuel  and  chimney  draft;  with  formulas  explained  or  practically  computed. 
255  pages,  179  illustrations.  Price $3.00 

Horsepower  Chart. 

Shows  the  horsepower,  of  any  stationary  engine  without  calculation.  No  matter  what  the 
cylinder  diameter  of  stroke,  the  steam  pressure  of  cut-off,  the  revolutions,  or  whether  con- 
densing or  non-condensing,  it's  all  there.  Easy  to  use,  accurate,  and  saves  time  and  calcula- 
tions. Especially  useful  to  engineers  and  designers.  Price 50  Cents 

STEAM  HEATING  AND  VENTILATION 

Practical  Steam,  Hot-Water  Heating  and  Ventilation.    By  A.  G.  KING. 

This  book  is  the  standard  and  latest  work  published  on  the  subject  and  has  been  prepared  for 
the  use  of  all  engaged  in  the  business  of  steam,  hot-water  heating,  and  ventilation.  It  is  an 
original  and  exhaustive  work.  Tells  how  to  get  heating  contracts,  how  to  install  heating  and 
ventilating  apparatus,  the  best  business  methods  to  be  used,  with  "Tricks  of  the  Trade"  for 
shop  use.  Rules  and  data  for  estimating  radiation  and  cost  and  such  tables  and  information 
as  make  it  an  indispensable  work  for  everyone  interested  in  steam,  hot-water  heating,  and 
ventilation.  It  describes  all  the  principal  systems  of  steam,  hot-water,  vacuum,  vapor,  and 
vacuum-vapor  heating,  together  with  the  new  accelerated  systems  of  hot-water  circulation, 
including  chapters  on  up-to-date  methods  of  ventilation  and  the  fan  or  blower  system  of  heat- 
ing and  ventilation.  Containing  chapters  on:  I.  Introduction.  II.  Heat.  III.  Evolution 
of  artificial  heating  apparatus.  IV.  Boiler  surface  and  settings.  V.  The  chimney  flue. 
VI.  Pipe  and  fittings.  VII.  Valves,  various  kinds.  VIII.  Forms  of  radiating  surfaces.  IX. 


32        THE    NORMAN    W.    HENLEY    PUBLISHING    CO. 

Locating  of  radiating  surfaces.  X.  Estimating  radiation.  XI.  Steam-heating  apparatus. 
XII.  Exhaust-steam  heating.  XIII.  Hot-water, heating.  XIV.  Pressure  systems  of  hot-water 
work.  XV.  Hot-water  appliances.  XVI.  Greenhouse  heating.  XVII.  Vacuum  vapor  and 
vacuum  exhaust  heating.  XVIII.  Miscellaneous  heating.  XIX.  Radiator  and  pipe  connec- 
tions. XX.  Ventilation.  XXI.  Mechanical  ventilation  and  hot-blast  heating.  XXII. 
Steam  appliances.  XXIII.  District  heating.  XXIV.  Pipe  and  boiler  covering.  XXV.  Tem- 
perature regulation  and  heat  control.  XXyi.  Business  methods.  XXVII.  Miscellaneous. 
XXVIII.  Rules,  tables,  and  useful  information.  367  pages,  300  detailed  engravings.  2nd 
Edition— Revised.  Price $3.00 

Five  Hundred  Plain  Answers  to  Direct  Questions  on  Steam,  Hot-Water, 
Vapor  and  Vacuum  Heating  Practice.    By  ALFRED  G.  KING. 

This  work,  jnst  off  the  press,  is  arranged  in  question  and  answer  form;  it  is  intended  as  a 
guide  and  text-book  for  the  younger,  inexperienced  fitter  and  as  a  reference  book  for  all 
fitters.  This  book  tells  "how"  and  also  tells  "why".  No  work  of  its  kind  has  ever  been 
published.  It  answers  all  the  questions  regarding  each  method  or  system  that  would  be 
asked  by  the  steam  fitter  or  heating  contractor,  and  may  be  used  as  a  text  or  reference  book, 
and  for  examination  questions  by  Trade  Schools  or  Steam  Fitters'  Associations.  Rules,  data, 
tables  and  descriptive  methods  are  given,  together  with  much  other  detailed  information  of 
daily  practical  use  to  those  engaged  in  or  interested  in  the  various  methods  of  heating.  Val- 
uable to  those  preparing  for  examinations.  Answers  every  question  asked  relating  to  modern 
Steam,  Hot-Water,  Vapor  and  Vacuum  Heating.  Among  the  contents  are:  The  Theory  and 
Laws  of  Heat.  Methods  of  Heating.  Chimneys  and  Flues.  Boilers  for  Heating.  Boiler 
Trimmings  and  Settings.  Radiation.  Steam  Heating.  Boiler,  Radiator  and  Pipe  Connec- 
tions for  Steam  Heating.  Hot  Water  Heating.  The  Two-Pipe  Gravity  System  of  Hot  Water 
Heating.  The  Circuit  System  of  Hot  Water  Heating.  The  Overhead  System  of  Hot  Water 
Heating.  Boiler,  Radiator  and  Pipe  Connections  for  Gravity  Systems  of  Hot  Water  Heat- 
ing. Accelerated  Hot  Water  Heating.  Expansion  Tank  Connections.  Domestic  Hot  Water 
Heating.  Valves  and  Air  Valves.  Vacuum  Vapor  and  Vacuo-Vapor  Heating.  Mechanical 
Systems  of  Vacuum  Heating.  Non-Mechanical  Vacuum  Systems.  Vapor  Systems.  Atmos- 
pheric and  Modulating  Systems.  Heating  Greenhouses.  Information,  Rules  and  Tables. 
200  pages,  127  illustrations.  Octavo.  Cloth.  Price $1 .50 


STEEL 

Steel:    Its  Selection,  Annealing,  Hardening,  and  Tempering.    By  E.  R. 

MARKHAM. 

This  work  was  formerly  known  as  "The  American  Steel  Worker,"  but  on  the  publication 
of  the  new,  revised  edition,  the  publishers  deemed  it  advisable  to  change  its  title  to  a  more 
suitable  one.  It  is  the  standard  work  on  Hardening,  Tempering,  and  Annealing  Steel  of  all  kinds. 
This  book  tells  how  to  select,  and  how  to  work,  temper,  harden,  and  anneal  steel  for  every- 
thing on  earth.  It  doesn't  tell  how  to  temper  one  class  of  tools  and  then  leave  the  treatment 
of  another  kind  of  tool  to  your  imagination  and  judgment,  but  it  gives  careful  instructions 
for  every  detail  of  every  tool,  whether  it  be  a  tap,  a  reamer  or  just  a  screw-driver.  It  tells 
about  the  tempering  of  small  watch  springs,  the  hardening  of  cutlery,  and  the  annealing  of 
dies.  In  fact,  there  isn't  a  thing  that  a  steel  worker  would  want  to  know  that  isn't  included. 
It  is  the  standard  book  on  selecting,  hardening  and  tempering  all  grades  of  steel.  Among 
the  chapter  headings  might  be  mentioned  the  following  subjects:  Introduction;  the  work- 
man; steel;  methods  of  heating;  heating  tool  steel;  forging;  annealing;  hardening  baths; 
baths  for  hardening;  hardening  steel;  drawing  the  temper  ^ after  hardening;  examples  of 
hardening;  pack  hardening;  case  hardening;  spring  tempering;  making  tools  of  machine 
steel;  special  steels;  steel  for  various  tools;  causes  of  trouble;  high-speed  steels,  etc.  400 
pages.  Very  fully  illustrated.  Fourth  edition.  Price $2.50 

Hardening,  Tempering,  Annealing,  and  Forging  of  Steel.    By  J.  V.  WOOD- 
WORTH. 

A  new  work  treating  in  a  clear,  concise  manner  all  modern  processes  for  the  heating,  anneal- 
ing, forging,  welding,  hardening  and  tempering  of 'steel,  making  it  a  book  of  great  practical 
value  to  the  metal-working  mechanic  in  general,  with  special  directions  for  the  successful 
hardening  and  tempering  of  all  steel  tools  used  in  the  arts,  including  milling  cutters,  taps,  thread 
dies,  reamers,  both  solid  and  shell,  hollow  mills,  punches  and  dies,  and  all  kinds  of  sheet- 
metal  working  tools,  shear  blades,  saws,  fine  cutlery,  and  metal-cuttina;  tools  of  all  descrip- 
tion, as  well  as  for  all  implements  of  steel  both  large  and  small.  In  this  work  the  simplest 
and  most  satisfactory  hardening  and  tempering  processes  are  given. 

The  uses  to  which  the  leading  brands  of  steel  may  be  adapted  are  concisely  presented,  and 
their  treatment  for  working  under  different  conditions  explained,  also  the  special  methods 
for  the  hardening  and  tempering  of  special  brands. 

A  chapter  devoted  to  the  different  processes  for  case-hardening  is  also  included,  and  special 
reference  made  to  the  adaptation  of  machinery  steel  for  tools  of  various  kinds.  Fourth  edi- 
tion. 288  pages.  201  illustrations.  Price $2.50 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS    33 
TRACTORS 


The  Modern  Gas  Tractor.    By  VICTOR  W.  PAGE,  M.E. 

A  complete  treatise  describing  all  types  and  sizes  of  gasoline,  kerosene  and  oil  tractors.  Con- 
siders design  and  construction  exhaustively,  gives  complete  instructions  for  care,  operation 
and  repair,  outlines  all  practical  applications  on  the  road  and  in  the  field.  The  best  and 
latest  work  on  farm  tractors  and  tractor  power  plants.  A  work  needed  by  farmers,  students, 
blacksmiths,  mechanics,  salesmen,  implement  dealers,  designers,  and  engineers.  Second  edition, 
revised  and  enlarged.  504  pages.  Nearly  300  illustrations  and  folding  plates.  Price  $2.00 


TURBINES 


Marine   Steam   Turbines.    By  DR.  G.  BAUER   and   O.  LASCHE.     Assisted  by 
E.  LUDWIG  and  H.  VOGEL. 

Translated  from  the  German  and  edited  by  M.  G.  S.  Swallow.  The  book  is  essentially  prac- 
tical and  discusses  turbines  in  which  the  full  expansion  of  ste^am  passes  through  a  number 
of  separate  turbines  arranged  for  driving  two  or  more  shafts,  as  in  the  Parsons  system,  and 
turbines  in  which  the  complete  expansion  of  steam  from  inlet  to  exhaust  pressure  occurs  in 
a  turbine  on  one  shaft,  as  in  the  case  of  the  Curtis  machines.  It  will  enable  a  designer  to 
carry  out  all  the  ordinary  calculation  necessary  for  the  construction  of  steam  turbines,  hence 
it  fills  a  want  which  is  hardly  met  by  larger  and  more  theoretical  works.  Numerous  tables, 
curves  and  diagrams  will  be  found,  which  explain  with  remarkable  lucidity  the  reason  why 
turbine  blades  are  designed  as  they  are,  the  course  which  steam  takes  through  turbines  of 
various  types,  the  thermodynamics  of  steam  turbine  calculation,  the  influence  of  vacuum 
on  steam  consumption  of  steam  turbines,  etc.  In  a  word,  the  very  information  which  a  de- 
signer and  builder  of  steam  turbines  most  requires.  Large  octavo,  214  pages.  Fully  illustrated 
and  containing  eighteen  tables,  including  an  entropy  chart.  Price,  net $3.50 


WATCH  MAKING 

Watchmaker's  Handbook.     By  CLAUDIUS  SAUNIER. 

No  work  issued  can  compare  with  this  book  for  clearness  and  completeness.  It  contains 
498  pages  and  is  intended  as  a  workshop  companion  for  those  engaged  in  watch-making  and 
allied  mechanical  arts.  Nearly  250  engravings  and  fourteen  plates  are  included.  This  is 
the  standard  work  on  watch-making.  Price $3 .00 


WELDING 


Automobile  Welding  with  the  Oxy- Acetylene  Flame.     By  M.  KEITH  DUNHAM. 

Explains  in  a  simple  manner  apparatus  to  be  used,  its  care,  and  how  to  construct  necessary 
shop  equipment.  Proceeds  then  to  the  actual  welding  of  all  automobile  parts,  in  a  manner 
understandable  by  every  one.  Gives  principles  never  to  be  forgotten.  Aluminum,  cast  iron, 
steel,  copper,  brass,  bronze,  and  malleable  iron  are  fully  treated,  as  well  as  a  clear  explana- 
tion of  the  proper  manner  to  burn  the  carbon  out  of  the  combustion  head.  This  book  is  of 
utmost  value,  since  the  perplexing  problems  arising  when  metal  is  heated  to  a  melting  point 
are  fully  explained  and  the  proper  methods  to  overcome  them  shown.  167  pages,  fully  illus- 
trated. Price $1.00 


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UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 

Return  to  desk  from  which  borrowed. 
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